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FORTRAN 77 Language Reference

1. The above program produces the following output 82 CacheBoard 1000 00 96K 232 FORTRAN 77 Language Reference May 2000 RETURN A RETURN statement returns control to the calling program unit RETURN e Parameter Description e Expression of type INTEGER or REAL Description Execution of a RETURN statement terminates the reference of a function or subroutine Execution of an END statement in a function or a subroutine is equivalent to the execution of a RETURN statement The expression e is evaluated and converted to integer if required e defines the ordinal number of the alternate return label to be used Alternate return labels are specified as asterisks or ampersands in the SUBROUTINE statement If e is not specified or the value of e is less than one or greater than the number of asterisks or ampersands in the SUBROUTINE statement that contains the RETURN statement control is returned normally to the statement following the CALL statement that invoked the subroutine If the value of e is between one and the number of asterisks or ampersands in the SUBROUTINE statement control is returned to the statement identified by the eth alternate A RETURN statement can appear only in a function subprogram or subroutine Chapter4 Statements 233 Examples Example 1 Standard return HARACTER 25 TEXT TEX
2. VMS Double Precision Complex TABLE 6 9 VMS Double Precision Complex Functions Generic Specific Name Names Function Argument Type Result Type CDABS Absolute value COMP LEX 16 REAL 8 CDEXP Exponential e a COMP LEX 16 COMP LEX 16 CDLOG Natural log COMPLEX 16 COMPLEX 16 CDSORT Square root COMPLEX 16 COMPLEX 16 CDSIN Sine COMP LEX 16 COMPLEX 16 CDCOS Cosine COMP LEX 16 COMP LEX 16 DCMPLX Convert to DOUBLE COMPLEX Any numeric COMP LEX 16 DCONJG Complex conjugate COMP LEX 16 COMP LEX 16 DIMAG Imaginary part of complex COMP LEX 16 REAL 8 DREAL Real part of complex COMP LEX 16 REAL 8 VMS Degree Based Trigonometric TABLE 6 10 VMS Degree Based Trigonometric Functions Generic Specific Name Names Function Argument Type Result Type SIND Sine SIND REAL 4 REAL 4 DSIND REAL 8 REAL 8 QSIND REAL 16 REAL 16 COSD Cosine COSD REAL 4 REAL 4 DCOSD REAL 8 REAL 8 QCOSD REAL 16 REAL 16 TAND Tangent TAND REAL 4 REAL 4 DTAND REAL 8 REAL 8 QTAND REAL 16 REAL 16 ASIND Arc sine ASIND REAL 4 REAL 4 DASIND REAL 8 REAL 8 QASIND REAL 16 REAL 16 Chapter 6 Intrinsic Functions 5 Result Type 4 8 1 6 4 8 1 6 4 8 1 6 Result Type TEGER 2 TEGER 4 TEGER 2 TEGER 4 TEGER
3. COMP LEX 32 lor2 QCMPLX INTEGER COMPLEX 32 See Note 8 REAL COMPLEX 32 DOUBLE COMP LEX 32 REAL 16 COMP LEX 32 COMP LEX COMP LEX 32 COMP LEX 16 COMP LEX 32 COMP LEX 32 COMP LEX 32 INTEGER 1 ICHAR CHARACTER INTEGER See Note 5 IACHAR 8 CHARACTER 1 CHAR INTEGER CHARACTER See Note 5 ACHAR 8 On an ASCII platform including Sun systems m ACHAR is a nonstandard synonym for CHAR IACHAR is a nonstandard synonym for ICHAR On a non ASCII platform ACHAR and IACHAR were intended to provide a way to deal directly with ASCII 330 FORTRAN 77 Language Reference May 2000 EX EX EX EX 331 Function Type REAL DOUBLE REAL 16 COMPLE DOUBLE COMP DOUBLE COMP COMPLEX 32 J O C Ww Q 0 ES Intrinsic Functions EX EX EX EX Argument Type REAL DOUBLE REAL 16 COMPLE DOUBLE COMP DOUBLE COMP COMPLEX 32 Chapter 6 Trigonometric Functions Specific Names SIN DSIN QSIN CSIN ZSIN CDSIN COSIN SIND DSIND QSIND COS DCOS QCOS CCOS 2005 02005 00005 amp 0050 DCOSD 00050 TAN DTAN QTAN TAND DTAND QTAND ASIN
4. Comments Compare to STRUCTURE and UNION C directive List directed Formatted Array M Implied Do Substring Character constant format Switch variable has format number Namelist List directed Formatted Array M Implied Do Substring Character constant FORTRAN Statement Samples Continued TABLE B 1 Examples MAP CHARACTER 18 MAJOR END MAP MAP INTEGER 2 CREDITS CHARACTER 8 GRAD_DATE END MAP ELIST CASE S N D UNIT 3 FILE data test UNIT 3 IOSTAT ERRNO S CHECK EXTEND_SOURCE NAI OPEN OPEN OPTIO PARAMETER A xyz PI 3 14 PARAMETER A z PI 3 14 PARAMETER X 11 Y X 3 PAUSE POINTER P V I X AL RNG SPRAGMA C RNG 10 M I I Jd K 10 C I K A6 13 A 1 FMT A6 I3 A I S I FMT s 1 FORTRAN 77 Language Reference May 2000 EXTER RINT RINT RINT RINT RINT RINT RINT PROGRAM FIDDLE PRINT PRINT PRINT az 0 0 P READ READ READ R R R Name Map NAMELIST amp OPEN OPTIONS amp PARAMETER PAUSE POINTER PRAGMA 9 PROGRAM PRINT READ 360 TABLE 8 1 FORTRAN Statement Samples Continued Examples Comments READ 1 2 Y Formatted read from a file
5. Miscellaneous Functions Other miscellaneous functions include bitwise functions environmental inquiry functions and memory allocation and deallocation functions Function Type R EGE QA Bit Manipulation None of these functions are part of the FORTRAN 77 Standard Argument Type R EGE 0 1 1 Specific Name NOT AND IAND LSHIFT RSHIFT LRSHFT ISHFTC IBITS IBS BITES IBC Bitwise Functions No of Args 1 NN NN NN N w FORTRAN 77 Language Reference May 2000 TABLE 6 6 Bitwise Operations Complement And Inclusive or Exclusive or Shift See Note 14 Left shift See Note 14 Right shift See Note 14 Logical right shift See Note 14 Circular shift Bit extraction Bit set Bit test Bit clear 336 337 The above functions are available as intrinsic or extrinsic functions See also the discussion of the library bit manipulation routines in the Fortran Library Reference manual Environmental Inquiry Functions None of these functions are part of th
6. INTEGER For a declaration such as INTEGER H the variable H is usually one INTEGER 4 element in memory interpreted as a single integer number Specifying the size is nonstandard If you do not specify the size a default size is used The default size for a declaration such as INTEGER H can be altered by compiling with any of the options dbl i2 28 or xt ypemap See the discussion in Chapter 2 for details INTEGER 2 4 For a declaration such as INTEGER 2_ H the variable H is always an INTEGER 2 element in memory interpreted as a single integer number INTEGER 4 4 For a declaration such as INTEGER 4 H the variable H is always an INTEGER 4 element in memory interpreted as a single integer number INTEGER 8 a4 For a declaration such as INTEGER 8 H the variable H is always an INTEGER 8 element in memory interpreted as a single integer number Restrictions Do not use INTEGER 8 variables or 8 byte constants or expressions when indexing arrays otherwise only 4 low order bytes are taken into account This action can cause unpredictable results in your program if the index value exceeds the range for 4 byte integers Chapter4 Statements 187 Examples Example 1 Each of these integer declarations are equivalent INTEGER U 9 INTEGER 4 U V 9 INTEGER U 4 V 9 4 Q Q Examp
7. EAL 100 100 Q 2 2 CALL SBRX Q 1 2 D SUBROUTINE SBRX A D E REAL A 100 100 D E RETURN END In this example the real array M matches the real array A and the real array element Q 1 2 matches the real variable D Chapter4 Statements 105 Example 5 A structured record and field the record is nonstandard STRUCTURE PRODUCT INTEGER 4 ID CHARACTER 16 NA CHARACTER 8 MODEL REAL 4 COST REAL 4 PRICI 4 END STRUCTURE RECORD PRODUCT CURRENT PRIOR CALL SBRX CURRENT PRIOR ID END SUBROUTINE SBRX NEW K STRUCTURE PRODUCT INTEGER 4 ID CHARACTER 16 NA CHARACTER 8 MODEL REAL 4 COST REAL 4 PRICI D STRUCTURE ECORD PRODUCT NEW E4 RETURN END In the above example the record NEW matches the record CURRENT and the integer variable K matches the record field PRIOR OLD 106 FORTRAN 77 Language Reference May 2000 CHARACTER The CHARACTER statement specifies the type of a symbolic constant variable array function or dummy function to be character Optionally it initializes any of the items with values and specifies array dimensions CHARACTER len v len c Parameter Description v Name of a symbolic constant variable arr
8. K amp 2 END demo 77 silent DoNest1 f DoNest1l f line 4 Warning DO range never executed demo a out I 11 J 10 K 5 N 0 L 0 demo The inner loop is not executed and at the WRITE L is undefined Here L is shown as 0 but that is implementation dependent do not rely on it Example 2 The program DoNest2 f DO variable always defined INTEGER COUNT OUTER COUNT 0 DO OUTER 1 5 NIN INNER COUNT COUNT 1 END DO OUTER NOUT INNER NIN COUNT tl WRIT END Chapter4 Statements 129 The above program prints out 6 5 3n 15 130 FORTRAN 77 Language Reference May 2000 DO WHILE The DO WHILE statement repeatedly executes a set of statements while the specified condition is true DO s WHILE e Parameter Description 5 Label of an executable statement e Logical expression Description Execution proceeds as follows The specified expression is evaluated If the value of the expression is true the statements in the range of the DO WHILE loop are executed If the value of the expression is false control is transferred to the statement following the DO WHILE loop Terminal Statement If s is specified the statement identified by it is called the terminal statement and it must follow the DO WHILE statement The termin
9. Size n 9 7 4 1 Data NodeAId NodeAId NodeAId NodeAId Format A7 A7 A7 A7 Memory NodeAIdAA NodeAId eAlId d A indicates a blank space Example Output strings of 3 5 and 7 characters each in a 5 character field PRINT 1 The whole shebang 1 FORMAT A5 A5 A5 END The above program displays AAThe whole sheba 282 FORTRAN 77 Language Reference May 2000 The maximum characters in noncharacter types are summarized in the following table TABLE 5 5 Maximum Characters in Noncharacter Type Hollerith nHaaa Type of List Item Maximum Number of Characters BYTE LOGICAL 1 LOGICAL 2 LOGICAL 4 LOGICAL 8 INTEGER 2 INTEGER 4 INTEGER 8 REAL REAL 4 REAL 8 REAL 16 SPARC only DOUBLE PRECISION COMP LEX COMP LEX 8 COMP LEX 16 16 COMPLEX 32 SPARC only 32 DOUBLE COMPLEX 16 m 00 00 6 00 00 60 7 In 77 you can use Hollerith constants wherever a character constant can be used in FORMAT statements assignment statements and DATA statements These constants are not recommended FORTRAN does not have these old Hollerith nH notations although the FORTRAN Standard recommends implementing the Hollerith feature to improve compatibility with old programs But such constants cannot be used as ELIST input input data elements in list directed or NAMI For example these two formats are equivalent 10 FORMAT 8H Code
10. Transfers the items to the external record or to an internal file m Terminates formatted output records with newline characters Example Formatted write REAL A 1 0 B 9 0 WRITE 6 10 A B 10 FORMAT F8 3 F6 2 For formatted write statements the logical record length is determined by the format statement that interacts with the list of input or output variables I O list at execution time For formatted write statements if the external representation of a datum is too large for the field width specified the specified field is filled with asterisks For formatted read statements if there are fewer items in the list than there are data fields the extra fields are ignored FORTRAN 77 Language Reference May 2000 274 77 Extensions B aaa A Ew d e Dw d e Gw d e Ow m nR R SU Format Specifiers FORTRAN 77 BN BZ space O 1 nH Aw aaa Dw dEe Ew dEe Fw dEe Gw dEe Iw m Lw nX Tn TLn TRN nP S SP SS TABLE 5 2 Format Specifiers Purpose Blank control Carriage control Character edit Floating point edit Hexadecimal edit Integer edit Logical edit Octal edit Position control Radix control Remaining characters Scale control Sign control Terminate a format Variable format expression Specifiers can be uppercase as well as lowercase characters in format statements and in all the alphabe
11. Example 2 Direct unformatted write trap I O errors and I O status Statements WRITE 1 REC 3 IOSTAT N ERR 8 V 4 CONTINUE RETURN 8 WRITE I O error on 1 END Example 3 Direct alternate syntax equivalent to above example WRITE 1 3 IOSTAT N ERR 8 V 4 CONTINUE RETURN 8 WRITE I O error on 1 END Chapter 4 Example 4 List directed write to screen WRITE PRINT A V R 8 ijklmnop Example 5 Formatted write to an internal file CHARACTER CA 16 L 8 abcdefgh WRITE CA 1 L R 1 FORMAT 2 A8 Example 6 Write an entire array DIMENSION V 5 WRITE 3 5F4 1 V Example 7 Namelist directed write HARACTER SAMPLE 16 LOGICAL NEW 4 REAL DELTA 4 NAMELIST G SA Q PLE NEW DELTA WRI E 1 G or WRITE UNIT 1 NML G or WRITE 1 NML G FORTRAN 77 Language Reference May 2000 262 CHAPTER 5 Input and Output This chapter describes the general concepts of FORTRAN input and output and provides details on the different kinds of I O See also the Input Output chapter in the Fortran Programming Guide Essential FORTRAN I O Concepts Any operating system based on the UNIX operating system is not as record oriented
12. An external unit identifier must be one of these A nonnegative integer expression An asterisk identifying stdin normally connected to the keyboard If the optional characters UNIT are omitted from the unit specifier then u must be the first item in the list of specifiers Format Identifier fis a format identifier and can be An asterisk indicating list directed I O See List Directed I O on page 312 for more information A label of a FORMAT statement that appears in the same program unit m An integer variable name that has been assigned the label of a FORMAT statement that appears in the same program unit a A character expression or integer array specifying the format string This is called a runtime format or a variable format The integer array is nonstandard See Runtime Formats on page 305 for details on formats evaluated at runtime If the optional characters FMT are omitted from the format specifier then f must appear as the second argument for a formatted read otherwise it must not appear at all Unformatted data transfer from internal files and terminal files is not allowed hence f must be present for such files List directed data transfer from direct access and internal files is allowed hence f can be an asterisk for such files If a file is connected for formatted I O unformatted data transfer is not allowed and vice versa I O Status Specifier ios mu
13. Examples Example 1 Complex variables These statements are equivalent 5 COMPLEX U 1 9 0 V 4 0 COMPLEX U 8 V 8 COMPLEX U V COMPLEX 8 U V Example 2 Initialize complex variables A complex constant is a pair of numbers either integers or reals Example 3 Double complex with initialization V 16 4 0 5 0D0 XY 4 0D0 5 0 oO 1 0D0 1 0D0 COMPLEX U 16 COMPLEX 16 X A double complex constant is a pair of numbers and at least one number of the pair must be double precision Example 4 Quadruple complex with initialization SPARC only V 32 4 0 4 000 li 0 9 9 1 000 1 000 COMPLEX U 32 COMPLEX 32 X A quadruple complex constant is a pair of numbers and at least one number of the pair must be quadruple precision Example 5 Complex arrays all of which are nonstandard SPARC only 5 16 5 32 8 S 5 5 5 COMPLEX R 16 COMPLEX U 32 5 COMPLEX X 8 5 FORTRAN 77 Language Reference May 2000 116 CONTINUE The CONTINUE statement is a do nothing statement label CONTINUE Parameter Description label Executable statement number Description The CONTINUE statement is often used as a place to hang a statement label usually it is the end of a DO loop INUE statement is
14. Input data items can be preceded by repetition counts as in 611 4 2 4 3 2 The above input stands for 4 complex constants 2 null input fields and 4 string constants A slash in the input list terminates assignment of values to the input list during list directed input and the remainder of the current input line is skipped Any text that follows the slash is ignored and can be used to comment the data line Output Format List directed output provides a quick and easy way to print output without fussing with format details If you need exact formats use formatted I O A suitable format is chosen for each item and where a conflict exists between complete accuracy and simple output form the simple form is chosen Note these rules for list directed output FORTRAN 77 Language Reference May 2000 312 In general each record starts with a blank space For a print file that blank is not printed See Printing Files on page 266 for details 5 m Character strings are printed as is They are not enclosed in quotes so only certain forms of strings can be read back using list directed input These forms are described in the next section A number with no exact binary representation is rounded off Example No exact binary representation demo cat lis5 f READ 5 WRITE 6 beauty WRITE 6 1 X 1 FORMAT 1X 13 8 truth
15. PARAMETER INODE Warning INODE corrupted The intrinsic function LEN INODE returns the actual declared length of a character string This is mainly for use with CHAR dummy arguments Example 6 The LEN intrinsic function CHARACTER A 17 A xyz PRINT LEN A END The above program displays 17 not 3 Chapter4 Statements 9 CLOSE The CLOSE statement disconnects a file from a unit CLOSE UNIT u STATUS sta IOSTAT ios ERR s Parameter Description u Unit identifier for an external unit If UNIT is not used then u must be first sta Determines the disposition of the file sta is a character expression whose value when trailing blanks are removed can be KEEP or DELETE The default value for the status specifier is KEEP For temporary scratch files sta is forced to DELETE always For other files besides scratch files the default sta is KEEP ios I O status specifier ios must be an integer variable or an integer array element s Error specifier s must be the label of an executable statement in the same program containing the CLOSE statement The program control is transferred to this statement in case an error occurs while executing the CLOSE statement Description The options can be specified in any order The DISP and DISPOSE options are allowable alternates for STATUS with a warning if the ansi flag is set
16. R R Argument Type EGER 2 ER 4 ER 2 ER 4 ER 2 ER 4 ER 2 ER 4 EG EG EG EG EG EG EG Specific Names Function FLOATI Convert to REAL 4 FLOATJ Convert to REAL 4 DFLOTI Convert to REAL 8 DFLOTJ Convert to REAL 8 AIMAXO Maximum AJMAX0 Maximum AIMINO Minimum AJMINO Minimum Zero Extend The following zero extend functions are recognized by 77 The first unused high order bit is set to zero and extended toward the higher order end to the width Result Type INTEGER 2 INTEGER 4 Argument Type LOGICAL 1 LOGICAL 2 ER 2 EG aN IN BY LOGICAL 1 LOGICAL 2 LOGICAL 4 R ER 2 ER 4 EG EG EG IN IN IN indicated in the table TABLE 6 15 Zero Extend Functions Specific Generic Name Names Function ZEXT Zero extend IZEXT Zero extend JZEXT Zero extend 350 FORTRAN 77 Language Reference May 2000 APPENDIX A ASCII Character Set This appendix contains two tables ASCII character sets and control characters 4 KX 0504 278 0000 0 2 35 020 TaQAMAAA TD gt 6 0 Hex Oct 140 141 142 143 144 145 146 147 150 151 152 153 154 155 156 157 160 161 162 163 164 165 166 167 170 17
17. on 1 END Example 3 List directed read from keyboard CHARACTER CA 16 abcdefghijklmnop L 8 R 8 EAD CA 1 L R AT 2 A8 Chapter4 Statements 225 ELTA V Example 5 Read an entire array ENSION V 5 D 3 5F4 1 Example 6 Namelist directed read 16 READ UNIT 1 NML G AMELIST G SAMPLE HARACTER SAMPLE OGICAL NEW 4 REAL DELTA 4 READ 1 G or or READ 1 NML G FORTRAN 77 Language Reference May 2000 226 REAL The REAL statement specifies the type of a symbolic constant variable array function or dummy function to be real and optionally specifies array dimensions and size and initializes with values REAL len v len c v len c Parameter Description v Name of a variable symbolic constant array array declarator function or dummy function len Either 4 8 or 16 SPARC only the length in bytes of the symbolic constant variable array element or function FAL 16 c List of constants for the immediately preceding name EAL 8 and RI Chapter 4 Statements 227 FAL 4 RI A Description Following are descriptions for RE REAL For a declaration such as REAL W the variable w is usually a REAL 4 element in memory interpreted as a real number Specifying the size is nonstan
18. 4 The Dw and Dw d edit specifiers indicate that the field to be edited occupies w positions d indicates that the fractional part of the number the part to the right of the decimal point has d digits However if the input datum contains a decimal point that decimal point overrides the d value On input the specified list item becomes defined with a real datum On output the specified list item must be defined as a real datum FORTRAN 77 Language Reference May 2000 294 In an output statement the D edit descriptor does the same thing as the E edit descriptor except that a D is used in place of an E The output field for the Dw d edit specifier has the width w The value is right justified in that field The field consists of zero or more leading blanks followed by either a minus if the value is negative or an optional plus followed by the magnitude of the value of the list item rounded to d decimal digits w must allow for a minus sign at least one digit to the left of the decimal point the decimal point and d digits to the right of the decimal point Therefore it must be the case that w d 3 Example Real input with D editing in the program Dinp f CHARACTER LINE 24 12345678 23 5678 345678 READ LINE D8 3 D8 3 D8 3 R S T PRINT D10 3 D11 4 D13 6 R S T END The above program displays 0 123D 05 0 2357D 02 0 345678D 00 In the
19. Chapter4 Statements 157 k R k defaults to 10 k P k defaults to 0 B BN and BZ S SU SP and SS Tn and nT TL n and TR n n defaults to 1 n x n defaults to 1 See Formatted I O on page 273 for full details of these edit descriptors Description The FORMAT statement includes the explicit editing directives to produce or use the layout of the record It is used with formatted input output statements and ENCODE DECODE statements Repeat Factor r must be a nonzero unsigned integer constant Repeatable Edit Descriptors The descriptors I 0 Z F E D G L and A indicate the manner of editing and are repeatable w and e are nonzero unsigned integer constants d and m are unsigned integer constants Nonrepeatable Edit Descriptors The descriptors are the following C 2 B BN BZ H P R Q S SU SP SS T TL TR X These descriptors indicate the manner of editing and are not repeatable m Each ai is any ASCII character nis a nonzero unsigned integer constant kis an optionally signed integer constant FORTRAN 77 Language Reference May 2000 158 Item Separator Items in the format specification list are separated by commas A comma can be omitted before or after the slash and colon edit descriptors between a P edit descriptor and the immediately following F E D or G edit descriptors In some sense th
20. ERR s Parameter Description u Unit identifier of the unit connected to the file f Format identifier ios I O status specifier rn Record number s Error specifier statement label iolist List of variables grname Name of the namelist group The options can be specified in any order An alternate for the REC rn form is allowed as follows WRITE u rn iolist amp See Example 3 later on in this section Description Unit Identifier u is either an external unit identifier or an internal file identifier An external unit identifier must be one of the following A nonnegative integer expression Chapter4 Statements 257 An asterisk identifying stdout which is normally connected to the console If the optional characters UNIT are omitted from the unit specifier then u must be the first item in the list of specifiers Format Identifier fis a format identifier and can be a An asterisk indicating list directed I O See List Directed I O on page 312 for more information m The label of a FORMAT statement that appears in the same program unit m An integer variable name that has been assigned the label of a FORMAT statement that appears in the same program unit m A character expression or integer array that specifies the format string This is called a runtime format or a variable format The integer array is nonstandard See Runtime Form
21. Execution of CLOSE proceeds as follows 1 The specified unit is disconnected 2 If sta is DELETE the file connected to the specified unit is deleted 3 If an IOSTAT argument is specified ios is set to zero if no error was encountered otherwise it is set to a positive value FORTRAN 77 Language Reference May 2000 110 Comments All open files are closed with default sta at normal program termination Regardless of the specified sta scratch files when closed are always deleted Execution of a CLOSE statement specifying a unit that does not exist or a unit that has no file connected to it has no effect Execution of a CLOSE statement specifying a unit zero standard error is not allowed but you can reopen it to some other file The unit or file disconnected by the execution of a CLOSE statement can be connected again to the same or a different file or unit Note For tape I O use the TOPEN routines Examples Example 1 Close and keep CLOSE 2 STATUS KEEP Example 2 Close and delete 2 STATUS DELETE IOSTAT I OPEN 2 STATUS SCRATCH CLOSE 2 STATUS KEEP IOSTAT I1 Chapter4 Statements 1 COMMON The COMMON statement defines a block of main memory storage so that different program units can share the same data without using arguments COMMON cb nlist cb nli
22. WRITE 2 2 FORMAT This is an apostrophe END The above program writes this message twice This is an apostrophe Chapter5 Input and Output 277 Blank Editing B BN BZ The B BN and BZ edit specifiers control interpretation of imbedded and trailing blanks for numeric input The following blank specifiers are available BN If BN precedes a specification a nonleading blank in the input data is considered null and is ignored BZ If BZ precedes a specification a nonleading blank in the input data is considered zero B If B precedes a specification it returns interpretation to the default mode of blank interpretation This is consistent with S which returns to the default sign control Without any specific blank specifiers in the format nonleading blanks in numeric input fields are normally interpreted as zeros or ignored depending on the value of the BLANK suboption of OPEN currently in effect for the unit The default value for that suboption is ignore so if you use defaults for both BN BZ B and BLANK you get ignore Example Read and print the same data once with BZ and once with BN demo cat 5 12341234 CHARACTER LINE 18 82 82 READ LINE 14 BZ 14 PRINT READ LINE 14 BN 14 PRINT END demo 77 silent bzl f demo a out 82 8200
23. With r8 or dbl INTEGER 8 LOGICAL 8 REAL 8 REAL 16 COMP LEX 16 COMP LEX 32 TABLE 2 2 Data Defaults Changed by i2 Default Type With i2 INTEGER INTEGER 2 LOGICAL LOGICAL 2 REAL REAL 4 DOUBLE REAL 8 COMP LEX COMP LEX 8 DOUBLE COMPLEX COMPLEX 16 Do not combine i2 with r8 as this can produce unexpected results REAL 16 and COMPLEX 32 are SPARC only With db1 or 28 INTEGER and LOGICAL are allocated the larger space indicated above This is done to maintain the FORTRAN requirement that an integer item and a real item have the same amount of storage However with r8 8 bytes are allocated but only 4 byte arithmetic is done With db1 8 bytes are allocated and full 8 byte arithmetic is done In all other ways db1 and r8 produce the same results A disadvantage of using r8 or db1 is that it also promotes DOUBLE ECISION possibly degrading performance PRECISION data to QUAD PR Use of the more flexible xt ypemap option is preferred over the older r8 and db1 options Both db1 and r8 have their ypemap equivalents 128 integer 64 128 integer mixed 64 integer 64 64 integer mixed On SPARC dbl sameas xtypemap real 64 double 28 sameas xtypemap real 64 double On x86 dbl same as xtypemap real 64 double 28 sameas xtypemap real 64 double The mapping integer mixed indicates 8 byte integer
24. 6 ABxyzz The final z comes from C2 78 FORTRAN 77 Language Reference May 2000 Variable Receiving Value Comment C2 ZA A trailing blank ol abcd Z wxyz BELL 07 hex Control G a bell Example 4 A Hollerith assignment CHARACTER S 4 INTEGER I2 2 14 4 REAL R S 4Hwxyz I I R 2 2Hyz 4 4Hwxyz ll ws HwxyZ Rules of Assignment Here are the rules for character assignments If the left side is longer than the right it is padded with trailing blanks If the left side is shorter than the right trailing characters are discarded The left and right sides of a character substring assignment cannot overlap See the Substrings on page 54 Chapter 3 Expressions 9 Logical Expressions A logical expression is a sequence of one or more logical operands and logical operators It evaluates to a single logical value The operators can be any of the following TABLE 3 4 Logical Operators Operator Standard Name AND Logical conjunction OR Logical disjunction inclusive OR NEQV Logical nonequivalence XOR Logical exclusive OR EQV Logical equivalence NOT Logical negation The period delimiters are necessary Two logical operators cannot appear consecutively unless the second one is the NOT operator Logical operators are evaluated according to the following precedence TABLE 3 5 Logical Operato
25. DO 126 DO WHILE 131 DOUBLE COMPLEX 134 DOUBLE PRECISION 136 ELSE 137 ELSE IF 139 ENCODE DECODE 141 END 142 END DO 3 END FILE 144 END IF 146 END MAP 7 END STRUCTURE 148 END UNION 149 ENTRY 150 EQUIVALENCE 153 EXTERNAL 155 FORMAT 157 FUNCTION External 161 GO TO Assigned 164 GO TO Computed 166 GO TO Unconditional 168 IF Arithmetic 9 IF Block 170 IF Logical 173 IMPLICIT 174 INCLUDE 177 INQUIRE 180 INTEGER 186 INTEGER 187 INTRINSIC 9 LOGICAL 191 06102 192 MAP 194 NAMELIST 195 OPEN 197 OPTIONS 205 PARAMETER 207 PAUSE 210 POINTER 212 PRINT 217 PROGRAM 220 READ 221 REAL 227 REAL 228 RECORD 230 RETURN 233 REWIND 235 SAVE 237 Statement Function 239 viii FORTRAN 77 Language Reference May 2000 STATIC 2 STOP 3 STRUCTURE 244 SUBROUTINE 247 TYPE 249 The Type Statement 250 UNION and MAP 3 VIRTUAL 255 VOLATILE 256 WRITE 257 Input and Output 263 Essential FORTRAN I O Concepts 263 Direct Access 270 Internal Files 2 Formatted I O 3 Unformatted I O 307 Binary I O 0 List Directed I O 312 NAMELISTI O 315 Intrinsic Functions 325 Arithmetic and Mathematical Functions 326 Character Functions 335 Miscellaneous Functions 336 Remarks 338 Notes on Functio
26. EGER 4 M ICOUNT 1 JCOUNT 4 TEMP ICOUNT B 0001000 UNT ICOUNT 0 777 EMP X FFF99A E M JCOUNT TEMP O pH a 5 3 T H H 0 Chapter 2 Data Types and Data Items 3 In the above example the context defines B 0001000 and 0 777 as INTEGER 4 and X FFF99A as REAL 4 For a real number using IEEE floating point a given bit pattern yields the same value on different architectures The above statements are treated as the following M ICOUNT 8 JCOUNT ICOUNT 511 TEMP 2 35076E 38 Control Characters You can enter control characters with typeless constants although the CHAR function is standard and this way is not Example Control characters with typeless constants CHARACTE ELL ETX X 03 PARAMETE ELL 07 Alternate Notation for Typeless Constants For compatibility with other versions of FORTRAN the following alternate notation is allowed for octal and hexadecimal notation This alternate does not work for binary nor does it work in DATA or PARAMETER statements For an octal notation enclose a string of octal digits in apostrophes and append the letter O Example Octal alternate notation for typeless constants S776 37 0 Invalid missing initial apostrophe r37 Not numeric missing letter O 397 0 Invalid i
27. If an end of file Control D is received before the input list is satisfied input stops and unsatisfied items of the input list remain unchanged If u specifies an external unit that is not connected to a file an implicit OPEN operation is performed equivalent to opening the file with the options in the following example OPEN u FILE FORT u STATUS OLD ACCESS SEQUENTIAL amp FORM fmt Note also The value of fmt is FORMATTED or UNFORMATTED accordingly as the read is formatted or unformatted FORTRAN 77 Language Reference May 2000 224 A simple unsubscripted array name specifies all of the elements of the array in memory storage order with the leftmost subscript increasing more rapidly An attempt to read the record of a direct access file that has not been written causes all items in the input list to become undefined The record number count starts from one Namelist directed input is permitted on sequential access files only Examples Example 1 Formatted read trap I O errors EOF and I O status READ 1 2 ERR 8 END 9 IOSTAT N X Y 8 WRITE I O error on 1 STOP 9 WRITE EoF on 1 RETURN END Example 2 Direct unformatted read trap I O errors and I O status READ 1 REC 3 IOSTAT N ERR 8 V 4 CO INUE RETURN 8 WRITE I O error
28. If you put an exclamation mark in any column of the statement field except within character literals then everything after the on that line is a comment A totally blank line is a comment line Example c C d D and blank comments Start expression analyzer CHARACTER S STACK 80 COMMON PRMS N S STACK Crack the expression IF S GE 0 AND S LE 9 THEN EoL comment CALL PUSH Save on stack EoL comment d PRINT S Debug comment amp EoL comment ELSE CALL TOLOWER To lowercase EoL comment END IF D PRINT N Debug comment amp EoL comment 0 Finished l expression analyzer Directives A directive passes information to a compiler in a special form of comment Directives are also called compiler pragmas There are two kinds of directives Chapter 1 Elements of FORTRAN General directives Parallel directives See the Sun WorkShop Fortran User s Guide and the Fortran Programming Guide for details on the specific directives available with 77 General Directives The form of a general directive is one of the following m CSPRAGMA id m CSPRAGMA id a a 2 4 CSPRAGMA SUN id options The variable id identifies the directive keyword a is an argument Syntax A directive has the following syntax Incolumn one any of the comment indicator characters c C or In any colum
29. READ UNIT 1 FMT 2 X Y READ 1 2 ERR 8 END 9 X Y READ UNIT 1 FMT 2 ERR 8 END 9 X Y READ 2 Y Formatted read from standard input READ 10 M Array M READ 10 M I I J K Implied Do READ 10 C I K Substring READ 1 List directed from file READ Jie ee from standard input READ 1 A6 I3 Y Character constant format READ 1 FMT A6 1I3 Y READ 1 C Y READ 1 FMT C Y READ 1 S Y Switch variable has format READ 1 FMT S X Y number READ G Namelist read READ 1 G Namelist read from a file 5 READ 1 END 8 ERR 9 X Y Unformatted direct access READ 1 REC 3 V Unformatted direct access READ 1 3 V READ 1 2 REC 3 V Formatted direct access READ CA 1 END 8 ERR 9 X Y Internal formatted sequential READ CA END 8 ERR 9 X Y Internal list directed sequential access 9 READ CA REC 4 END 8 ERR 9 Y Internal direct access REAL R M 4 REAL R 4 ed REAL 8 A B C Double precision REAL 16 A B C SPARC only Quad precision REAL A 3 14 B 0 100 0 Initialize A and Cx RECORD PROD CURR PRIOR NEXT RETURN Standard return RETURN 2 Alternate return Appendix B Sample Statements 1 Name REAL RECORD RETURN TABLE 8 1 FORTRAN Sta
30. TABLE 5 3 Default w d e Values in Format Field Descriptors 6 TABLE 5 4 Carriage Control with Blank 0 1 and 9 TABLE 5 5 Maximum Characters in Noncharacter Type Hollerith nHaaa 283 TABLE 5 6 Sample Octal Hex Input Values 288 TABLE 5 7 Sample Octal Hex Output Value 289 TABLE 5 8 Default Formats for List Directed Output 314 TABLE 6 1 Arithmetic Functions 7 TABLE 6 2 Type Conversion Functions 329 TABLE 6 3 Trigonometric Functions 1 TABLE 6 4 Other Mathematical Functions 333 TABLE 6 5 Character Functions 335 TABLE 6 6 Bitwise Functions 336 TABLE 6 7 Environmental Inquiry Functions 337 TABLE 6 8 Memory Functions 338 TABLE 6 9 VMS Double Precision Complex Functions 5 TABLE 6 10 VMS Degree Based Trigonometric Functions 5 TABLE 6 11 VMS Bit Manipulation Functions 346 TABLE 6 12 VMS Integer Functions 348 TABLE 6 13 Translated Functions that VMS Coerces to a Particular Type 349 TABLE 6 14 VMS Functions That Are Translated into 77 Generic Names 0 TABLE 6 15 Zero Extend Functions 0 TABLE A 1 ASCII Character Set 2 TABLE A 2 Control Characters Control Key s Shift and Control Keys 3 TABLE B 1 FORTRAN Statement Samples 355 TABLE C 1 Floating point Representation 365 TABLE C 2 IEEE Representation of Selected Numbers 7 TABLE C 3 Extreme Value Abbreviations 367 xii FORTRAN 77 Language Reference May 2000 xiii Tables Extreme Values Addition and Subtraction 368 Extreme Values Multiplication 368 Extreme Val
31. X Y WRITE 1 2 ERR 8 END 9 X Y WRITE UNIT 1 FMT 2 ERR 8 END 9 X Y WRITE 2 Y WRITE 10 WRITE 10 M I I J K WRITE 10 C I K WRITE 1 Y WRITE Y WRITE 1 26 13 Y WRITE 1 FMT A6 I3 Y WRITE 1 C Y WRITE 1 FMT C Y WRITE 1 S WRITE 1 FMT S WRITE CASE WRITE 1 CASE WRITE 1 END 8 ERR 9 X Y WRITE 1 REC 3 V WRITE Tm Bye SM WRITE 1 2 REC 3 V WRITE CA 1 END 8 ERR 9 X Y WRITE CA END 8 ERR 9 X Y WRITE CA REC 4 END 8 ERR 9 X Y Appendix Sample Statements 3 Name WRITE 364 FORTRAN 77 Language Reference May 2000 APPENDIX 6 Data Representations Whatever the size of the data element in question the most significant bit of the data element is always stored in the lowest numbered byte of the byte sequence required to represent that object This appendix is a brief introduction to data representation For more in depth explanations see the Sun WorkShop Fortran Programming Guide and Numerical Computation Guide Real Double and Quadruple Precision Real double precision and quadruple precision number data elements are represented according to the IEEE standard by the following form where f is the bits in the fraction Quad is SPARC only 1 si8 pexponent bias 1 T
32. opt SUNWspro lt release gt include f 77 verl usr include For a non standard install to a directory mydir replace opt with mydir The lt release gt path changes with each compiler release Chapter4 Statements 179 INQUIRE The INQUIRE statement returns information about a unit or file u slist slist INQUIRE UNIT INQUIRE FILE fn Parameter Description fn Name of the file being queried the file being queried 1 Number of slist The specifiers list slist can include one or more of the following in any order ex 8 EXIST OPENED od nmd NAMED ACCESS acc QUENTIAL seq DIRECT dir RM fm RMATTED fmt FORMATTED unf e SE 0 FO UNE NAME fn blnk BLANK e IOSTAT ios NUMBER num RECL rel NEXTREC nr Description You can determine such things about a file as whether it exists is opened or is connected for sequential I O That is files have such attributes as name existence or nonexistence and the ability to be connected in certain ways FORMATTED UNFORMATTED SEQUENTIAL or DIRECT Inquire either by unit or by file but not by both in the same statement In this system environment the only way to discover what permissions you have for E statement does not determine ESS 3F function The INQUIRI FORTRAN 77 Language Reference May 2000 a file is to
33. 2 0 9 In the above example the compiler starts to evaluate the but it needs to know what power to raise X to so it looks at the rest of the expression and must choose between and It first does the then the then the Mixed Mode Except for BYTE operands if both operands have the same type then the resulting value has that type The result of an arithmetic operation with both operands type BYTE is default integer If operands have different types then the weaker of two types is promoted to the stronger type where the weaker type is the one with less precision or fewer storage units The ranking is summarized in the following table Data Type Rank BYTE or LOGICAL 1 1 Weakest LOGICAL 2 LOGICAL 4 INTEGER 2 INTEGER 4 INTEGER 8 LOGICAL 8 REAL 4 REAL REAL 8 DOUBLE PRECISION REAL 16 QUAD PRECISION SPARC only COMPLEX 8 COMPLEX COMPLEX 16 DOUBLE COMPLEX 10 COMPLEX 32 QUAD COMPLEX SPARC only 11 Strongest 00 4 0 0 WN O 72 FORTRAN 77 Language Reference May 2000 Note REAL 4 INTEGER 8 and LOGICAL 8 are of the same rank but they can be the results of different pairs of operands For example INTEGER 8 results if you combine INTEGER 8 and any of the types between 1 5 Likewise REAL 4 results if one of the operands is REAL 4 and the other is any of the types between 1 5 LOGICAL 8 dictates only the 8 byte size of the res
34. 2 FORMAT 1X 12 1X 8021 END demo cat qed2 data qwerty demo 77 qed2 2 ged2 f MAIN demo qed2 6 qwerty demo The above example gets the length of the input record With the whole input string 301 and its length you can then parse it yourself Chapter 5 Input and Output Several restrictions on the Q edit descriptor apply The list element Q corresponds to must be of INTEGER or LOGICAL data type does strictly a character count It gets the number of characters remaining in the input record and does not get the number of integers or reals or anything else The Q edit descriptor cannot be applied for pipe files as Q edit requires that the file be rereadable m This descriptor operates on files and stdin terminal input m This descriptor is prohibited for output and will generate a runtime error Scale Factor P The P edit descriptor scales real input values by a power of 10 It also gives you more control over the significant digit displayed for output values The general form is k P Parameter Description k Integer constant with an optional sign k is called the scale factor and the default value is zero Example I O statements with scale factors READ 1 32 88 2 WRITE 1 1P 88 2 X P by itself is equivalent to OP It resets the scale factor to the default value OP Just P b
35. 22 026 L6 SYN V Synchronous idle 23 027 L7 ETB W End of transmission blocks 24 030 L8 CAN X Cancel 25 031 L9 EM OY End Of medium 26 032 LA Ss AZ Special sequence 27 033 LB ESC s K Escape 28 034 LC FS s L File separator 29 035 LD GS s M Group separator 30 036 LE RS s N Record separator 31 037 LF US s O Unit separator 127 177 TE DEL s 0 Delete or rubout _ Appendix A ASCII Character Set 3 354 FORTRAN 77 Language Reference May 2000 APPENDIX B Sample Statements This appendix shows a table that contains selected samples of the 77 statement types The purpose is to provide a quick reference for syntax details of the more common variations of each statement type Nonstandard features are tagged with a small black cross TABLE B 1 FORTRAN Statement Samples Examples Comments ACCEPT A I Compare to READ ASSIGN 9 TO I C abc Character C abc C 8 abc C S 1I M L 21 OR 2 Logical LE 80 1 Arithmetic 1 Hex 00000 7 X CURR NEXT Compare to NEXT ID 82 RECORD AUTOMATIC A B C AUTOMATIC REAL P D Q IMPLICIT AUTOMATIC REAL 2 BACKSPACE U BACKSPACE UNIT U IOSTAT I ERR 9 BLOCK DATA BLOCK DATA COEFFS 355 Name ACCEPT ASSIGN ASSIGNMENT AUTOMATIC BACKSPACE BLOCK DATA Comments Initialize A and B Altern
36. 26 20 FORMAT Code 26 In 77 commas between edit descriptors are generally optional Chapter5 Input and Output 3 10 FORMAT 5H flex 4Hible Reading Into Hollerith Edit Descriptors For compatibility with older programs 77 also allows READs into Hollerith edit descriptors Example Read into hollerith edit descriptor no list in the READ statement demo cat holl f WRITE 1 1 FORMAT 6Holder READ 1 WRITE 1 END demo 77 holl f hod Ste MAT demo a out older newer newer demo In the above code if the format is a runtime format variable format then the reading into the actual format does not work and the format remains unchanged Hence the following program fails HARACTER F 18 8 EAD F lt Does not work Obviously there are better ways to read into the actual format Integer Editing 1 The I specifier is used for decimal integer data items The general form is I w m The Iw and Iw m edit specifiers indicate that the field to be edited occupies w positions The specified input output list item must be of type integer On input the specified list item becomes defined with an integer datum On output the specified list item must be defined as an integer datum FORTRAN 77 Language Reference May 2000 284 On input an Iw m edi
37. EOF Opens a file at end of file rather than at the beginning useful for appending data to file for example FILEOPT EOF Unlike ACCESS APPEND in this case both READ and BACKSPACE are allowed READONLY 5 The file is opened read only ACTION act This specifier denotes file permissions Possible values are READ WRITE and READWRITE m If act is READ it specifies that the file is opened read only If act is WRITE it specifies that the file is opened write only You cannot execute a BACKSPACE statement on a write only file If act is READWRITE it specifies that the file is opened with both read and write permissions FORTRAN 77 Language Reference May 2000 202 Examples Here are six examples Example 1 Open a file and connect it to unit 8 either of the following forms of the OPEN statement opens the file projectA data test and connects it to FORTRAN unit 8 OPEN UNIT 8 FILE projectA data test OPEN 8 FILE projectA data test In the above example these properties are established by default sequential access formatted file and unwisely no allowance for error during file open Example 2 Explicitly specify properties UNIT 8 FILE projectA data test amp ESS SEQUENTIAL FORM FORMATTED Example 3 Either of these opens file fort 8 and connects it to uni
38. ER 4 ER 2 ER 4 ER 2 ER 4 H Na A Argument Type R 2 R 4 R 2 R 4 R 2 R 4 R 2 R 4 R 2 R 4 R 2 EGE EGE EGE EGE EGE R 4 EGE EGE EGE EGE EGE EGE EGE TABLE 6 12 VMS Integer Functions Function Absolute value Absolute value Maximum 1 Maximum 1 Minimum 1 Minimum 1 Positive difference 2 Positive difference 2 Remainder of a1 a2 Remainder of a1 a2 Transfer of sign la1l sign a2 Transfer of sign al1 sign a2 Specific Names IIABS JIABS IMAX0 JMAX0 IMINO JMINO IIDIM JIDIM IMOD JMOD IISIGN JISIGN 1 There must be at least two arguments 2 The positive difference is al min al a2 FORTRAN 77 Language Reference May 2000 348 Result Type INTEGER 2 INTEGER 4 INTEGER 8 INTEGER 2 INTEGER 4 INTEGER 2 INTEGER 4 INTEGER 2 INTEGER 4 INTEGER 2 INTEGER 4 INTEGER 2 INTEGER 4 INTEGER 2 INTEGER 4 INTEGER 2 INTEGER 4 INTEGER 2 INTEGER 4 Functions Coerced to a Particular Type EGER type Some VMS FORTRAN functions coerce to a particular INT TABLE 6 13 Translated Functions that VMS Coerces to a Particular Type Argument Type REAL 4 REAL 4 REAL 4 REAL 8 REAL 8 REAL 1
39. Hex 26 Octal hex 10 FORMAT 3F lt N gt 2 Variable expression FUNCTION FUNCTION 2 A B FUNCTION P D 9 CHARACTER FUNCTION R 4 P D 9 INTEGER 2 FUNCTION I J Short integer 5 GO TO GO TO 99 Unconditional GO TO I 10 50 99 Assigned GO TO I 60 TO 10 50 99 1 Computed 358 FORTRAN 77 Language Reference May 2000 Comments Arithmetic IF LOGICAL IF BLOCK IF BLOCK IF With ELSE IF Short integer Initialize A and C amp Pd Initialize B Sample Statements 359 FORTRAN Statement Samples Continued 90 IF C EQ 8 THEN EQ THEN Examples IF I K 10 50 IF L RETURN IF L THEN N N 1 CALL CALC ELSE K K 1 CALL DISP ENDIF NA NA 1 CALL APPEND ELSE IF C NB NB 1 CALL BEFORE ELSE IF C EQ c THEN IMPLICIT COMPLEX U W 2 IMPLICIT UNDEFINED A 2 INCLUDE project02 header INQUIRE UNIT 3 OPENED OK NQUIRE FILE mydata EXIST OK INQUIRE UNIT 3 OPENED OK Ci fie OF Appendix B NC NC 1 CALL CENTER END IF IOSTAT ERRNO INTEGER C D 4 INTEGER 02 INTEGER 4 A B C EGI R A 100 B INTRINSIC SQRT EXP LOGICAL 6 LOGICAL 1 C 1 LOGICAL 1 B C LOGICAL 4 A B C LOGICAL B FALSE TABLE B 1 Name IF IMPLICIT INCLUDE INQUIRE INTEGER INTRINSIC LOGICAL
40. LIMITS defined in the Example 2 You cannot associate storage of two different common blocks in the same program unit COMMON X A COMMON Y B IVALENCE A B Not allowed EQU Example 3 An EQUIVALENCE statement can extend a common block on the right ENSION A 5 hand side DIM ON X 8 IVALENCE B A COM EQU Example 4 An EQUIVALENCE statement must not cause a common block to be extended on the left hand side IVALENCE A B 2 Not allowed Chapter4 Statements 113 COMMON X A REAL B 2 EQU COMP LEX The COMPLEX statement specifies the type of a symbolic constant variable array function or dummy function to be complex optionally specifies array dimensions and size and initializes with values COMPLEX len v len c v len c Parameter Description v Name of a symbolic constant variable array array declarator function or dummy function len Either 8 16 or 32 the length in bytes of the symbolic constant variable array element or function 32 is SPARC only c List of constants for the immediately preceding name Description The declarations can be COMPLEX COMPLEX 8 COMPLEX 16 or COMPLEX 32 Specifying the size is nonstandard 114 FORTRAN 77 Language Reference May 2000 COMP LEX For a declaration such as COMPL
41. OpZ REAL 4 12 02 REAL 8 23 5 02 REAL 16 COMPLEX 2 44 L LOGICAL 2 F E D G REAL COMP LEX 8 15 7 2 276 FORTRAN 77 Language Reference May 2000 TABLE 5 3 Default w d 6 Values in Format Field Descriptors Continued Field Descriptor List Element w d e F E D G REAL 8 COMPLEX 16 25 16 2 F E D G REAL 16 COMPLEX 32 42 33 3 LOGICAL 1 1 LOGICAL 2 INTEGER 2 2 LOGICAL 4 INTEGER 4 4 REAL 4 COMPLEX 8 4 REAL 8 COMPLEX 16 8 2 REAL 16 COMPLEX 2 16 gt gt gt P p D P CHARACTER n n For complex items the value for w is for each real component The default for the A descriptor with character data is the declared length of the corresponding I O list element REAL 16 and COMPLEX 32 are SPARC only Apostrophe Editing aaa The apostrophe edit specifier is in the form of a character constant It causes characters to be written from the enclosed characters of the edit specifier itself including blanks An apostrophe edit specifier must not be used on input The width of the field is the number of characters contained in but not including the delimiting apostrophes Within the field two consecutive apostrophes with no intervening blanks are counted as a single apostrophe You can use quotes in a similar way Example apos f apostrophe edit two equivalent ways WRITE 1 1 FORMAT This is an apostrophe
42. S not allowed error message 82 Not DOUBLE PRECISION need decimal point or exponent 29 002 0D0 Invalid comma not allowed error message 1 8D308 Invalid too large machine infinity is used 1 0D 324 Invalid too small some precision is lost The restrictions are Other than the optional plus or minus sign a decimal point the digits 0 through 9 a blank and the letter D No other characters are allowed The magnitude of an IEEE normalized double precision floating point value must be in the approximate range 2 225074D 308 1 797693D 308 REAL 16 Quad Real Constants SPARC only A quadruple precision constant is a basic real constant or an integer constant such that it is followed by a quadruple precision exponent See Real Constants on page 39 A quadruple precision exponent consists of the letter Q followed by an optional plus or minus sign followed by an integer A quadruple precision constant can be positive negative or zero If no sign is present the constant is assumed to be nonnegative Example Quadruple precision constants 1 9 3 3 2 1 2 55 0 Invalid not allowed error message 82 Not quad need exponent 29 002 000 Invalid comma not allowed error message 1 605000 Invalid too large machine infinity is used 1 60 5000 Invalid too small some precision is lost The form and interpretation are the same as for a real constant except that a Q is used instead
43. Syntax Rules The POINTER statement has the following syntax 202 01 1 POINTER where v1 v2 are pointer based variables also called pointees pl p2 are the corresponding pointers A pointer based variable is a variable paired with a pointer in a POINTER statement A pointer based variable is usually just called a based variable or a pointee The pointer is the integer variable that contains the address Variable names appearing on a POINTER statement are considered VOLATILE by the compiler Example A simple POINTER statement POINTER P V Here V is a pointee and P is its associated pointer See POINTER on page 212 for more examples Usage of Pointers Normal use of pointer based variables involves the following steps The first two steps can be in either order Define the pairing of the pointer based variable and the pointer in a POINTER statement Define the type of the pointer based variable The pointer itself is integer type and should not appear in a type declaration Set the pointer to the address of an area of memory that has the appropriate size and type You do not normally do anything else explicitly with the pointer Reference the pointer based variable Just use the pointer based variable in normal FORTRAN statements the address of that variable is always from its associated pointer FORTRAN 77 Language
44. as FORTRAN This operating system treats files as sequences of characters instead of collections of records The FORTRAN runtime system keeps track of file formats and access mode during runtimes It also provides the file facilities including the FORTRAN libraries and the standard I O library Logical Units The FORTRAN default value for the maximum number of logical units that a program can have open at one time is 64 For current Solaris releases this limit is 256 A FORTRAN program can increase this limit beyond 64 by calling the setrlim function See the setrlim 2 man page If you are running csh you can also do this with the limit or unlimit command see csh 1 The standard logical units 0 5 and 6 are preconnected as stderr stdin and stdout respectively These are not actual file names and cannot be used for opening these units INQUIRE does not return these names and indicates that the above units are not named unless they have been opened to real files However these units can be redefined with an OPEN statement 263 The names stderr stdin and stdout are meant to make error reporting more meaningful To preserve error reporting the system makes it an error to close logical unit 0 although it can be reopened to another file If you want to open a file with the default file name for any preconnected logical unit remember to close the unit first Redefining the standard units can impair normal console I
45. if a 20 int a 5 ifa lt 0 int a 5 ifa gt 0 int a 5 ifa lt 0 al int al a2 a2 lall ifa2 gt 0 lall ifa2 lt 0 al a2 if al gt a2 0 if al lt a2 al a2 max al a2 See Note 1 Nearest whole number Nearest integer Remainder See Note 1 Transfer of sign Positive difference Double and quad products Choosing largest value Function ER Type REAL H Q Argument ER Type INTEG TABLE 6 1 Arithmetic Functions Continued Specific Names AMAX0 MAX1 MINO AMIN1 DMIN1 QMIN1 AMINO MIN1 No of Args Generic Intrinsic Function Definition Name AMAX0 MAX1 Choosing min al a2 lt 2 MIN smallest value AMINO MIN1 FORTRAN 77 Language Reference May 2000 328 329 Function Type EGE EGE EGE EGE EGE EGE EGE EGE 2 2 2 1 8 1 I 1 i I 1 zZ E e ee ee ECISIO ECISIO ECISIO ECISIO ECISIO ECISIO ECISIO ECISIO ECISIO ECISIO 0 O Ww 1 votes 00 0 Intrinsic Functions Argument Type
46. or to delimit character constants For more on character constants see the next section The following is sample data to be read by the program segment above AScase delta 0 05 mat 2 2 2 2 sample Demo Chapter5 Input and Output 319 The data could be on several records Here NEW was not input and the order is not the same as in the example NAMELIST statement AScase Adelta 0 05 Amat 2 2 2 Asample Demo AS Syntax Rules The following syntax rules apply for input data to be read by NAMELIST m The variables of the named group can be in any order and any can be omitted The data starts in or after column two It may start in column 1 but this is non standard There must be at least one comma space or tab between variables and one or more spaces or tabs are the same as a single space Consecutive commas are not permitted before a variable name Spaces before or after a comma have no effect No spaces or tabs are allowed inside a group name or a variable name except around the commas of a subscript around the colon of a substring and after the and before the marks No name can be split over two records m The end of a record acts like a space character Note an exception in a character constant it is ignored and the character constant is continued with the next record The last character of the current record is immediately followed b
47. the list item becomes defined with a logical datum On output the specified list item must be defined as a logical datum The input field consists of optional blanks optionally followed by a decimal point followed by a T for true or F for false The T or F can be followed by additional characters in the field The logical constants TRUE and FALSE are acceptable as input The output field consists of w 1 blanks followed by a T for true or F for false Example 101 5 logical output LOGICAL 1 TRUE B 2 TRUE C 4 FALSE PRINT 21 L2 24 A B C END The program above displays AT AAAF Example log2 5 logical input LOGICAL 4 A 1 READ L8 A PRINT A GO TO 1 END The program above accepts any of the following as valid input data t true 7 IRUBE wt be e T Te TRUE f false F FALSE f F FALSE Flakey 286 FORTRAN 77 Language Reference May 2000 Octal and Hexadecimal Editing 0 2 The 0 and Z field descriptors for a FORMAT statement are for octal and hexadecimal integers respectively but they can be used with any data type The general form is ow m zw m where w is the number of characters in the external field For output m if specified determines the total number of digits in the external field that is if there are fewer than m nonze
48. 0 For details see LOINIT 3F and the Sun Fortran Library Reference Example Attach external files inil inp and inil out to units 1 and 2 In sh demo TSTO1 inil inp demo TSTO2 inil out demo export TSTO1 TSTO2 In csh demo setenv TSTO1 inil inp demo setenv TSTO2 inil out Chapter5 Input and Output 9 Example Attach the files inil inp and inil out to units 1 and 2 demo cat inil f CHARACTER PRFX 8 LOGICAL CCTL BZRO APND VRBOSE DATA CCTL BZRO APND PRFX VRBOSE amp TRUE FALSE FALSE TST FALSE 06 CALL IOINIT 0072 2220 APND PRFX VRBOSE READ 1 I B N WRITE 1 I B WRITE 2 I B END demo cat TSTO1 12 3 14159012 6 demo 77 inil f ira t MAIN demo a out 12 B 3 14159 N 6 demo cat 2 12 3 14159 6 IOINIT should prove adequate for most programs as written However it is written in FORTRAN so that it can serve as an example for similar user supplied routines A copy can be retrieved from opt SUNWspro lt release gt src ioinit f The lt release gt path changes with each release of the compiler Direct Access A direct access file contains a number of records that are written to or read from by referring to the record number Direct access is also called random access In direct access Records must be
49. 1 See Note 17 Allocate Allocate memory and 1 return address See Note 17 Deallocate Deallocate memory 1 allocated by MALLOC See Note 17 Size Return the size of the 1 argument in bytes See Note 18 Although malloc 3F and free 3F are not strictly speaking intrinsics they are listed here and in the Fortran Library Reference Additional non standard intrinsics such as iset jmp 3F longjmp 3F and date_and_time 3F are also described in the Fortran Library Reference and by their man pages Remarks The following remarks apply to all of the intrinsic function tables in this chapter TEGER 4 or TEGER type ECISION PR F m The abbreviation DOUBLE stands for DOUBL m An intrinsic that takes INTEGER arguments accepts INTEGER 2 IN EGER arguments return values of I determined as follows note that options 12 db1 and xtypemap may alter INTEGER 8 m INTEGER intrinsics that take INT the default sizes of actual arguments m mod sign dim max min and iand or ior xor ieor size of the value returned is the largest of the sizes of the arguments m abs ishft lshift rshift 1285216 ibset btest ivclr ishftc ibits size of the value returned is the size of the first argument FORTRAN 77 Language Reference May 2000 338 int
50. 1 ERFC The error function 2 sqrt pi x integral from 0 to a of exp t t dt Intrinsic Function Common logarithm Error function See note below Error function FORTRAN 77 Language Reference May 2000 334 Function Type TEGER CHARACTER HARACTER INTEGER HARACTER INTEGER HARACTER INTEGER HARACTER LOGICAL HARACTER LOGICAL HARACTER LOGICAL HARACTER LOGICAL Argument Type I Character Functions Specific Names R CHA ACHAR amp ICHAR HAR 3 IAC No of Args Character Functions Definition Conversion to character Conversion to integer See also TABLE 6 2 Location of substring a2 in string al See Note 10 Length of character entity See Note 11 al lt 2 See Note 12 al gt 2 See Note 12 al lt a2 See Note 12 al gt 2 See Note 12 TABLE 6 5 Intrinsic Function Conversion See Note 5 Index of a substring Length Lexically greater than or equal Lexically greater than Lexically less than or equal Lexically less than On an ASCII platform including Sun systems m ACHAR is a nonstandard synonym for CHAR IACHAR is a nonstandard synonym for ICHAR On a non ASCII platform ACHAR and IACHAR were intended to provide a way to deal directly with ASCII Chapter 6 Intrinsic Functions 5
51. 2 end demo 77 silent Direct3 f demo a out As 1D 6 7 50 9 demo In the above example after reading 3 integers 12 bytes you start the next read at record 13 Binary I O Opening a file for binary I O allows the program to read and write data as a stream of binary data without record boundaries This feature is not standard Fortran 77 The FORM BINARY option on an OPEN statement declares that unit to be a sequential unformatted file without record marks OPEN 1 FORM BINARY A binary file cannot also be declared direct access or formatted On a WRITE statement binary data is written to the file as a stream of bytes as many as there are in the output list On a READ statement as many data bytes are read as demanded by the variables on the input list Since there are no record marks end of record in the file there will be no possibility of reading past a record mark Other 310 FORTRAN 77 Language Reference May 2000 EAD statement just reads the next sequence of bytes 311 than abnormal system errors the only situation that the program can detect is reading in the end of file Each RI in the file as shown in the following example program bin character 25 string character 5 word open 1 FORM BINARY string alphabetagammaepsilon write 1 string rewind 1 do 1 i 1 6 word 4 read 1 word print word en
52. 2000 Example Implicitly by its name as with variables UNCTION NXT F INTEGER X NXT X 1 RETUR Implicit typing can affect the type of a function either by default implicit typing or by an IMPLICIT statement You must make the data type of the function be the same within the function subprogram as it is in the calling program unit The 77 compiler does no type checking across program units Properties of Data Types This section describes the data types in Sun FORTRAN 77 Default data declarations those that do not explicitly declare a data size can have their meanings changed by certain compiler options The next section Size and Alignment of Data Types on page 31 summarizes data sizes and alignments and the effects of these options BYTE The BYTE data type provides a data type that uses only one byte of storage It is a logical data type and has the synonym LOGICAL 1 A variable of type BYTE can hold any of the following One eight bit data item m An integer between 128 and 127 The logical values TRUE or FALSE If it is interpreted as a logical value a value of 0 represents FALSE and any other value is interpreted as TRUE 77 allows the BYTE type as an array index just as it allows the REAL type but it does not allow BYTE as a DO loop index where it allows only INTEGER REAL and DOUBLE PRECISION Whe
53. 82 82 demo Note these rules for blank control m Blank control specifiers apply to input only A blank control specifier remains in effect until another blank control specifier is encountered or format interpretation is complete The B BN and BZ specifiers affect only I F E D and G editing FORTRAN 77 Language Reference May 2000 278 Carriage Control space 0 1 Use edit descriptor and space 0 or 1 for carriage control Dollar 5 The special edit descriptor suppresses the carriage return The action does not depend on the first character of the format It is used typically for console prompts For instance you can use this descriptor to make a typed response follow the output prompt on the same line This edit descriptor is constrained by the same rules as the colon Example The carriage control doll f The edit descriptor with space WRITE 2 2 FORMAT Enter the node number 5 READ NODENUM END The above code produces a displayed prompt and user input response such as Enter the node number 82 The first character of the format is printed out in this case a blank For an input statement the descriptor is ignored Space 0 1 and The following first character slew controls and actions are provided TABLE 5 4 Carriage Control with Blank 0 1 and Character Vertical spacing before prin
54. Describes the documentation available with this Sun WorkShop release and how to access it Provides information about the new features in the current and previous release of Sun WorkShop Contains installation details and other information that was not available until immediately before the final release of Sun WorkShop 6 This document complements the information that is available in the component readme files Explains how to use the new Sampling Collector and Sampling Analyzer with examples and a discussion of advanced profiling topics and includes information about the command line analysis tool er_print the LoopTool and LoopReport utilities and UNIX profiling tools prof gprof and tcov Provides information on using dbx commands to debug a program with references to how the same debugging operations can be performed using the Sun WorkShop Debugging window Acquaints you with the basic program development features of the Sun WorkShop integrated programming environment Document Title About Sun WorkShop 6 Documentation What s New in Sun WorkShop 6 Sun WorkShop 6 Release Notes Analyzing Program Performance With Sun WorkShop 6 Debugging a Program With dbx Introduction to Sun WorkShop TABLE P 3 Document Collection Forte Developer 6 Sun WorkShop 6 Release Documents Forte Developer 6 Sun WorkShop 6 FORTRAN 77 Language Reference May 2000 TABLE P 3 Related Su
55. EXIST ex a exis a logical variable that is set to TRUE if the file or unit exists and FALSE otherwise If the file is a link INQUIRE always returns TRUE even if the linked file does not exist FILE fn nis a character expression or with the name of the file Trailing blanks in the file name are ignored If the file name is all blanks that means the current directory The file need not be connected to a unit in the current program FORM fm m fm is a character variable which is assigned the value FORMATTED if the file is connected for formatted I O UNFORMATTED if the file is connected for unformatted I O BINARY if the file was opened for unstructured binary I O FORMATTED fmt m fmt is a character variable that is assigned the value YES if the file could be connected for formatted I O No if the file could not be connected for formatted I O and UNKNOWN if the system cannot tell TOSTAT 108 m ios is as in the OPEN statement NAME fn m fn is a character variable that is assigned the name of the file connected to the unit If you do an inquire by unit the name parameter is undefined unless both the values of the OPENED and NAMED variables are both true If you do an inquire by file the name parameter is returned even though the FORTRAN 77 Standard leaves it undefined NAMED nmd nmd is a logical variable that is assigned TRUE if the file has a
56. FORM fm IOSTAT ios RECL flor alternatively RECORDSIZE rl e STATUS sta alternatively TYPE sta e FILEOPT fopt READONLY 8 ACTION Description The OPEN statement determines the type of file named whether the connection specified is legal for the file type for instance DIRECT access is illegal for tape and tty devices and allocates buffers for the connection if the file is on tape or if the subparameter FILEOPT BUFFER n is specified Existing files are never truncated N routines Chapter4 Statements 197 F on opening Note For tape I O use the TOP specifiers Data Type of Variable CHARACTER CHARACTER CHARACTER INTEGER CHARACTER CHARACTER CHARACTER INTEGER INTEGER CHARACTER The following table summarizes the OPEN OPEN Statement Specifiers Value of Variable APPEND DIRECT SEQUENTIAL READ WRITE READWRITE NULL ZERO Statement number FORMATTED UNFORMATTED PRINT BINARY 3 Filename NOPAD BUFFER n EOF Error number Record length OLD NEW UNKNOWN SCRATCH TABLE 4 3 Form SPECIFIER Variable SPECIFIER ACCESS ACTION BLANK ERR FORM FILE FILEOPT IOSTAT READONLY RECL STATUS The keywords can be specified in any order OPEN Specifier Keywords The following provides a detailed
57. FORM PRINT the file acts like a FORM FORMATTED file except for interpretation of the column 1 characters on the output blank single space 0 double space 1 form feed and no advance If FORM UNFORMATTED each record is preceded and terminated with an INTEGER 4 count making each record 8 characters longer than normal This convention is not shared with other languages so it is useful only for communicating between FORTRAN programs FORM fm The FORM fm clause is optional fm is a character expression Possible values are FORMATTED UNFORMATTED BINARY or PRINT The default is FORMATTED This option interacts with ACCESS PRINT makes it a print file BINARY treats the file as a sequential unformatted file with no record marks Specifying ACCESS DIRECT or RECL n with FORM BINARY generates an error Each WRITE statement writes as many bytes in binary as there are in the data on the output list A READ statement reads as many bytes from the input file as are required by the input list Since no record marks are recognized it is not possible to read outside the record Other than abnormal system errors the only input error that can occur is reading the end of file BACKSPACE ona FORM BINARY file is not allowed and generates a runtime error RECL rl The RECLs frl clause is required if ACCESS DIRECT and ignor
58. Inc in the U S and other countries All SPARC trademarks are used under license and are trademarks or registered trademarks of SPARC International Inc in the U S and other countries Products bearing SPARC trademarks are based upon an architecture developed by Sun Microsystems Inc The OPEN LOOK and Sun Graphical User Interface was developed by Sun Microsystems Inc for its users and licensees Sun acknowledges the pioneering efforts of Xerox in researching and developing the concept of visual or graphical user interfaces for the computer industry Sun holds a non exclusive license from Xerox to the Xerox Graphical User Interface which license also covers Sun s licensees who implement OPEN LOOK GUIs and otherwise comply with Sun s written license agreements Sun 90 95 is derived from Cray CF90 a product of Silicon Graphics Inc Federal Acquisitions Commercial Software Government Users Subject to Standard License Terms and Conditions DOCUMENTATION IS PROVIDED AS IS AND ALL EXPRESS OR IMPLIED CONDITIONS REPRESENTATIONS AND WARRANTIES INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY FITNESS FOR A PARTICULAR PURPOSE OR NON INFRINGEMENT ARE DISCLAIMED EXCEPT TO THE EXTENT THAT SUCH DISCLAIMERS ARE HELD TO BE LEGALLY INVALID Copyright 2000 Sun Microsystems Inc 901 San Antonio Road Palo Alto CA 94303 4900 Etats Unis Tous droits r serv s Ce produit ou document est distribu avec des licences qui en restre
59. Input and Output 317 Note that if you do omit the keyword NML then the unit parameter must be first namelist specifier must be second and there must not be a format specifier The WRITE can have the form of the following example WRITE UNIT 6 NML CASE Input Actions The NAMELIST input statement reads the next external record skipping over column one and looking for the symbol in column two or beyond followed by the group name specified in the READ statement If the group name is not found the input records are read until end of file The records are input and values assigned by matching names in the data with names in the group using the data types of the variables in the group Variables in the group that are not found in the input data are unaltered The syntax of NAMELIST READ is READ extu namelist specifier iostat err end where namelist specifier has the form NML group name and group name has been previously defined in a NAMELIST statement Example NAMELIST input CHARACTER 14 SAMPLE LOGICAL 4 NEW REAL 4 DELTA MAT 2 2 N R AMELIST CASE SAMPLE NEW DELTA MAT EAD 1 CASE In this example the group CASE consists of the variables SAMPLE NEW DELTA and MAT If you do omit the keyword NML then you must also omit th
60. LOGICAL 4 29 30 of an expression 73 properties 25 384 FORTRAN 77 Language Reference May 2000 D 142 D DO 143 D FILE 144 D IF 146 D MAP 147 d D of text 77 STRUCTURE 148 D UNION 149 nd of line comments 19 372 TRY 150 environmental inquiry functions 337 epbase 337 ephuge 337 fo epmax 337 epmin 337 epmrsp 337 epprec 337 eptiny 337 equals statement 91 EQUIVALENCE 153 ERR INQUIRE 182 OPEN specifier 201 READ 223 WRITE 258 error I O 264 escape sequences 36 evaluation of expressions 85 executable statements 16 exponential editing 296 exponents in octal or hex input 288 expression arithmetic 70 71 character 76 constant 83 evaluation 85 logical 80 variable format 159 extended source lines 18 extensions 12 EXTERNAL 155 extract substring 54 Index 5 DOUBLE PRECISION 27 136 double quote 375 377 character constants 34 preceding octal constants 39 double spacing print 267 double complex arrays 135 constants 37 data type 27 double precision complex 27 complex function 344 data representation 365 editing 294 real constants 41 DREAL 329 dummy arguments and NAMELIST 316 E e 18 E format specifier 296 edit descriptor 304 304 281 294
61. O status specifier ios must be an integer variable or an integer array element 5 The error specifier statement label 5 must be the label of executable statement in the same program unit in which the ENCODE and DECODE statement occurs iolist List of input output items Description The entities in the I O list can be variables substrings arrays array elements record fields A simple unsubscripted array name specifies all of the elements of the array in memory storage order with the leftmost subscript increasing more rapidly Execution proceeds as follows 1 The ENCODE statement translates the list items to character form according to the format identifier and stores the characters in buf A WRITE operation on internal files does the same Chapter4 Statements 121 2 The DECODE statement translates the character data in buf to internal binary form according to the format identifier and stores the items in the list A READ statement does the same 3 If buf is an array its elements are processed in the order of subscript progression with the leftmost subscript increasing more rapidly 4 The number of characters that an ENCODE or a DECODE statement can process depends on the data type of buf For example an INTEGER 2 array can contain two characters per element so that the maximum number of characters is twice the number of elements in that array A cha
62. R x oO DW x E gt Wr N O x Oo lt x oO J e X 16 Chapter 6 1 E ExT E EX 32 2 EG INT REAL Type Conversion Type Conversion Functions Specific Names DBLE DF LOAT DREAL DBLEQ REAL QFLOAT EXT EXTD amp Q Q Generic Name INT DBLE QREALE QEXT No of Args 1 TABLE 6 2 Conversion to INTEGER See Note 1 EAL See Note 2 See Note 3 EAL 16 See Note 3 DOUBLE TABLE 6 2 Type Conversion Functions Continued No of Generic Specific Conversion to Args Name Names Argument Type Function Type COMP LEX 12 CMP LX fad INTEGER COMP LEX See Notes 4 REAL COMP LEX and 8 DOUBLE COMP LEX REAL 16 COMPLEX 2 COMP LEX COMP LEX COMPLEX 16 COMP LEX COMPLEX 32 COMPLEX DOUBLE 12 INTEGER DOUBLE COMPLEX COMP LEX REAL DOUBLE COMPLEX See Note 8 DOUBLE DOUBLE COMPLEX REAL 16 DOUBLE COMPLEX COMP LEX DOUBLE COMPLEX COMPLEX 16 DOUBLE COMPLEX COMP LEX 32 DOUBLE COMPLEX
63. SAVE However using SAVE can ensure portability especially with routines that leave a subprogram by some way other than a RETURN Restrictions The following constructs must not appear in a SAVE statement Variables or arrays in a common block Dummy argument names Record names Procedure names Automatic variables or arrays Chapter 4 Statements 237 Example Example A SAVE statement SUBROUTINE FFA N DIMENSION A 1000 1000 V 1000 SAVE A wD ETURN D 238 FORTRAN 77 Language Reference May 2000 Statement Function A statement function statement is a function like declaration made in a single statement fun idi d e Parameter Description fun Name of statement function being defined d Statement function dummy argument e Expression e can be any of the types arithmetic logical or character Description If a statement function is referenced the defined calculations are inserted Example The following statement is a statement function ROOT A 2 C B SORT B 2 4 0 A C 2 0 A The statement function argument list indicates the order number and type of arguments for the statement function A statement function is referenced by using its name along with its arguments as an operand in an expression Execution proceeds as follows If they are expressions actual arguments are evaluated Actual arguments are assoc
64. VMS version allows a module name and a LIST control directive that are indistinguishable from a continuation of a UNIX file name Also VMS ignores alphabetic case so if you are inconsistent about capitalization distinctions are made where none are intended Getting a long integer expecting a short In VMS FORTRAN you can pass a long integer argument to a subroutine that expects a short integer This feature works if the long integer fits in 16 bits because the VAX addresses an integer by its low order byte This feature does not work on SPARC systems Those VMS system calls that are directly tied to that operating system Initializing a common block in more than one subprogram Alphabetizing common blocks so you can rely or depend on the order in which blocks are loaded You can specify the older with the M mapfile option to 1d If you use the defaults for both of the following The OPEN option BLANK a The BN BZ B format edit specifiers then formatted numeric input ignores imbedded and trailing blanks The corresponding VMS defaults treat them as zeros Appendix VMS Language Extensions 379 380 FORTRAN 77 Language Reference May 2000 Nas 14 NUMERICS 0 1 vertical format control 279 A A format specifier 281 ACCEPT 88 374 access append option in open 199 modes 265 options in OPEN 199 SEQUENTIAL in OPEN file 199 two modes for accessing a file 265 ACHAR 330 addr
65. a generalization of an array Just as an array is a collection of elements of the same type a structure is a collection of elements that are not necessarily of the same type As elements of arrays are referenced by using numeric subscripts so elements of structures are referenced by using element or field names The structure declaration defines the form of a record by specifying the name type size and order of the fields that constitute the record Once a structure is defined and named it can be used in RECORD statements as explained in the following subsections Syntax The structure declaration has the following syntax STRUCTURE structure name field list field declaration field declaration field declaration END STRUCTURE structure name Name of the structure field list List of fields of the specified structure field declaration Defines a field of the record field declaration is defined in the next section Field Declaration Each field declaration can be one of the following a A substructure either another structure declaration or a record that has been previously defined A union declaration which is described later m A FORTRAN type declaration FORTRAN 77 Language Reference May 2000 56 Example A STRUCTURE declaration STRUCTURE PRODUCT TEGER 4 ID HARACTER 16 NAME HARACTER 8 MODEL EAL 4 COST EAL 4 PRICE END STRUCTURE w
66. all the same length m Records are usually all the same type A logical record in a direct access external file is a string of bytes of a length specified when the file is opened 270 FORTRAN 77 Language Reference May 2000 Read and write statements must not specify logical records longer than the original record size definition m Shorter logical records are allowed Unformatted direct writes leave the unfilled part of the record undefined a Formatted direct writes pass the unfilled record with blanks In using direct unformatted I O be careful with the number of values your program expects to read m Direct access READ and WRITE statements have an argument REC n which gives the record number to be read or written An alternate nonstandard form is n Unformatted I O Example Direct access unformatted OPEN 2 FILE data db ACCESS DIRECT RECL 20 amp FORM UNFORMATTED ERR 90 READ 2 REC 13 ERR 30 X Y READ 2 13 ERR 30 Y Alternate form This code opens a file for direct access unformatted I O with a record length of 20 characters then reads the thirteenth record as is Formatted I O Example Direct access formatted OPEN 2 FILE inven db ACCESS DIRECT RECL 20 amp FORM FORMATTED ERR 90 READ 2 FMT 110 F10 3 REC 13 ERR 30 A B This code
67. arrays to be arrays of variables with such structures RECORD struct name record list struct name record list Parameter Description struct_name Name of a previously declared structure record_list List of variables arrays or array declarators Description A structure is a template for a record The name of the structure is included in the STRUCTURE statement and once a structure is thus defined and named it can be used in a RECORD statement The record is a generalization of the variable or array where a variable or array has a type the record has a structure Where all the elements of an array must be of the same type the fields of a record can be of different types The RECORD line is part of an inherently multiline group of statements and neither the RECORD line nor the END RECORD line has any indication of continuation Do not put a nonblank in column six nor an amp in column one Structures fields and records are discussed in Structures on page 56 Restrictions m Each record is allocated separately in memory m Initially records have undefined values Records record fields record arrays and record array elements are allowed as arguments and dummy arguments When you pass records as arguments their fields must match in type order and dimension The record declarations in the calling and called procedures must match Within a union declaration the order of the
68. declarator specifies the name and properties of an array The syntax of an array declarator is where m ais the name of the array dis a dimension declarator A dimension declarator has the form dl du where a dl is the lower dimension bound 48 FORTRAN 77 Language Reference May 2000 du is the upper dimension bound An array must appear only once in an array declarator within a program unit main program subroutine function or block common The compiler flags multiple or duplicate array declarations within the same unit as errors The number of dimensions in an array is the number of dimension declarators The minimum number of dimensions is one the maximum is seven For an assumed size array the last dimension can be an asterisk The lower bound indicates the first element of the dimension and the upper bound indicates the last element of the dimension In a one dimensional array these are the first and last elements of the array Example Array declarator lower and upper bounds EAL V 5 5 In the above example V is an array of real numbers with 1 dimension and 1 elements The first element is V 5 the last element is V 5 Example Default lower bound of 1 EAL V 1000 In the above example V is an array of real numbers with 1 dimension and 1000 elements The first element is V 1 the last element is V 1000 Example Arrays can have as many
69. default is SEQUENTIAL If ACCESS APPEND SEQUENTIAL and FILEOPT EOF are assumed This is for opening a file to append records to an existing sequential access file Only WRITE operations are allowed although no error message is issued This is an extension and can be applied only to disk files If ACCESS DIRECT RECL must also be given since all I O transfers are done in multiples of fixed size records Only directly accessible files are allowed thus tty pipes and magnetic tape are not allowed If you build a file as sequential then you cannot access it as direct If FORM is not specified unformatted transfer is assumed If FORM UNFORMATTED the size of each transfer depends upon the data transferred If ACCESS SEQUENTIAL RECL is ignored The FORTRAN 77 Standard prohibits RECL for sequential access No padding of records is done If you build a file as direct then you cannot access it as sequential Files do not have to be randomly accessible in the sense that tty pipes and tapes can be used For tapes we recommend the TOPEN routines because they are more reliable If FORM is not formatted transfer is assumed Chapter4 Statements 199 If FORM FORMATTED each record is terminated with a newline n character that is each record actually has one extra character If
70. epbas pprec size of the value returned is the size of default INTEGER ephuge size of the value returned is the size of the default INTEGER or the size of the argument whichever is largest Options that change the default data sizes see Size and Alignment of Data Types on page 31 also change the way some intrinsics are used For example with db1 in effect a call to ZCOS with a DOUBLE COMPLEX argument will automatically become a call to CQCOS because the argument has been promoted to COMP LEX 32 The following functions have this capability aimag alog amod cabs ccbrt ccos cdabs cdcbrt cdcos cdexp cdlog cdsin cdsqrt cexp clog csin csqrt dabs dacos dacosd dasin dasind datan datand dcbrt dconjg dcos dcosd dcosh ddim derf derfc dexp dimag dint dlog dmod dnint dprod dsign dsin dsind dsinh dsqrt dtan dtand dtanh idnint iidnnt jidnnt zabs zcbrt 2008 zexp zlog zsin zsqrt The following functions permit arguments of an integer or logical type of any size and iand ieor iiand iieor iior inot ior jiand jieor jior jnot lrshft lshift not or rshift xor SPARC only An intrinsic that is shown to return a default REAL DOUBLE PRECISION COMPLEX or DOUBLE COMPLEX value will return the prevailing type depending on certain compilation options See Size and Alignment of Data Types on page 31 For example if compiled with xtypemap real 64 double 64 A call to a REAL fu
71. example the first input data item has no decimal point so E9 3 determines the decimal point The other input data items have decimal points so those decimal points override the D edit descriptor as far as decimal points are concerned Example Real output with editing in the program Eout f R 1234 678 PRINT 1 R R R 1 FORMAT E9 3 8 4 E13 4 END The above program displays 0 123E 04 AAAO 1235E 04 In the above example E8 4 does not allow for the sign so we get asterisks Also the extra wide field of the E13 4 results in three leading blanks Example Real output with Ew dEe editing in the program EwdEe f REAL X 0 000789 WRITE 13 3 WRITE 13 384 WRITE E13 3E5 END Chapter5 Input and Output 297 The above program displays AAAAO 78 9E 03 AAO 789E 0003 A0 789E 00003 F Editing The F specifier is for decimal real data items The general form is F w d The Fw and Fw d edit specifiers indicate that the field to be edited occupies w positions d indicates that the fractional part of the number the part to the right of the decimal point has d digits However if the input datum contains a decimal point that decimal point ove
72. executable reference to that variable is flagged as an error when compiling with the stackvar option See the Sun WorkShop Fortran User s Guide Taking into account the repeat factor the number of constants in clist must be equal to the number of items in the nlist The appearance of an array in nlist is equivalent to specifying a list of all elements in that array Array elements can be indexed by constant subscripts only Automatic variables or arrays cannot appear on a DATA statement Normal type conversion takes place for each noncharacter member of the clist FORTRAN 77 Language Reference May 2000 118 Character Constants in the DATA Statement If the length of a character item in nlist is greater than the length of the corresponding constant in clist it is padded with blank characters on the right If the length of a character item in nlist is less than that of the corresponding constant in clist the additional rightmost characters are ignored If the constant in clist is of integer type and the item of nlist is of character type they must conform to the following rules m The character item must have a length of one character The constant must be of type integer and have a value in the range 0 through 255 For A B C do not hold down the Control key and press A B or C use the CHAR intrinsic function If the constant of clist is a character constant or a Hollerith constant and the item of nlist is
73. field in the record immediately to the left Example References that are based on structure and records of the above two examples RECORD PRODUCT CURRENT PRIOR NEXT LINE 10 CURRENT NEXT LINE 1 CURRENT WRITE 9 CURRENT NEXT ID 82 In the above example The first assignment statement copies one whole record all five fields to another record m The second assignment statement copies a whole record into the first element of an array of records The WRITE statement writes a whole record The last statement sets the ID of one record to 82 Chapter 2 Data Types and Data Items 9 Example Structure and record declarations record and field assignments demo cat str1 f Simple structure STRUCTURE S INTEGER 4 I REAL 4 R END STRUCTURE RECORD S R1 R2 82 2 7182818 R1 WRITE R2 I R2 R demo 77 silent strl f demo a out 82 2 718280 Str Ris I R1 R R2 STOP END demo Substructure Declaration A structure can have a field that is also a structure Such a field is called a You can declare a substructure in one of two ways substructure A RECORD declaration within a structure declaration A structure declaration within a structure declaration nesting Record Within a Structure A nested structure declaration is one that is cont
74. hard coded every eight columns nX Positions The nX edit specifier indicates that the transmission of the next character to or from a record is to occur at the position n characters forward from the current position On input the nx edit specifier advances the record pointer by n positions skipping n characters A position beyond the last character of the record can be specified if no characters are transmitted from such positions On output the nX specifier writes n blanks The n defaults to 1 FORTRAN 77 Language Reference May 2000 290 Example Input Tn absolute tabs demo cat rtab f CHARACTER C 2 S 2 PEN 1 FILE mytab data 0 1 1 2 08 29 1 ORMAT 15 A2 Tl 22 PRINT END DO END demo 50 1 The two line data file is demo cat mytab data defguvwx 12345678 demo The run and the output are demo a out uvde 5612 demo The above example first reads columns 5 and 6 then columns 1 and 2 Example Output Tn absolute tabs this program writes an output file demo cat otab f CHARACTER C 20 12345678901234567890 OPEN 1 FILE mytab rep WRITE 1 2 C USA 7 2 FORMAT 220 T10 Al T20 Al END demo Chapter5 Input and Output 1 The output file is demo cat mytab rep 123456789 123456789 demo The above example write
75. in 77 Details are elsewhere in this manual Namelist I O Unlabeled Do END DO m Indefinite DO WHILE END DO BYTE data type Logical operations on integers and arithmetic operations on logicals m Additional field and edit descriptors for FORMAT statements Remaining characters Q Carriage Control a Octal 0 371 a Hexadecimal x a Hexadecimal z Default field indicators for w d and e fields in FORMAT statements Reading into Hollerith edit descriptors APPEND option for OPEN Long names 32 characters _ and in names Long source lines 132 character if the e option is on Records structures unions and maps Getting addresses by the LOC function Passing arguments by the VAL function End of line comments OPTIONS statement VMS Tab format source lines are valid Initialize in common You can initialize variables in common blocks outside of BLOCK DATA subprograms You can initialize portions of common blocks but you cannot initialize portions of one common block in more than one subprogram Radix 50 Radix 50 constants are implemented as 57 7 bit string constants that is no type is assumed IMPLICIT NONE is treated as IMPLICIT UNDEFINED A Z VIRTUAL is treated as DIMENSION Initialize in declarations Initialization of variables in declaration statements is allowed Example CHARACTER 10 NAME Nell Noncharact
76. map fields is not relevant Record fields are not allowed in COMMON statements FORTRAN 77 Language Reference May 2000 230 Records and record fields are not allowed in DATA EQUIVALENCE NAMELIST PARAMETER AUTOMATIC STATIC or SAVE statements To initialize records and record fields use the STRUCTURE statement See STRUCTURE on page 244 for more information Example Example 1 Declare some items to be records of a specified structure STRUCTURE PRODUCT TEGER 4 ID CHARACTER 16 CHARACTER 8 MODE REAL 4 COST REAL 4 PRIC D STRUCTURE ECORD PRODUCT CURRENT PRIOR NEXT LINE 10 H Each of the three variables CURRENT PRIOR and NEXT is a record which has the PRODUCT structure and LINE is an array of 10 such records Example 2 Define some fields of records then use them STRUCTURE PRODUCT INTEGER 4 ID CHARACTER 16 NAM CHARACTER 8 MOD REAL 4 COST REAL 4 PRICI D STRUCTURE ECORD PRODUCT CURRENT PRIOR NEXT LINE 10 URRENT ID 82 RIOR NA CacheBoard EXT PRICE 1000 00 LINE 2 MODEL 96K PRINT 1 CURRENT ID PRIOR NAME NEXT PRICE LINE 2 MODEL 1 FORMAT 1X I5 1X A16 1X F8 2 1X A8 END Dy 2 a 0 E Chapter4 Statements 231
77. much precision of the significant part of the real part of Aas a REAL 16 datum can contain If A is type COMPLEX 16 or COMPLEX 32 then QREAL A is the real part of A 4 CMPLX If A is type complex then CMPLX A is A If A is type integer real or double precision then CMPLX A is REAL A Oi If Al and A2 are type integer real or double precision then CMPLX A1 A2 is REAL A1 REAL A2 1i If A is type double complex then CMPLX A is REAL DBLE A i REAL DIMAG A If CMPLX has two arguments then they must be of the same type and they may be one of integer real or double precision If CMPLX has one argument then it may be one of integer real double precision complex COMPLEX 16 or COMPLEX 32 DCMPLX If A is type COMPLEX 16 then DCMPLX A is A If A is type integer real or double precision then DCMPLX A is DBLE A Oi If A1 and A2 are type integer real or double precision then DCMPLX A1 A2 is DBLE A1 DBLE A2 1i If DCMPLX has two arguments then they must be of the same type and they may be one of integer real or double precision If DCMPLX has one argument then it may be one of integer real double precision complex COMPLEX 16 or COMPLEX 32 5 ICHAR ICHAR A is the position of A in the collating sequence The first position is 0 the last is N 1 OSICHAR A 1 gt where is the nu
78. other character If you compile with the x1 option then the backslash character is treated as an ordinary character That is with the x1 option you cannot use these escape sequences to get special characters Technically the escape sequences are not nonstandard but are implementation defined Complex Constants A complex constant is an ordered pair of real or integer constants or PARAMETER constants The constants are separated by a comma and the pair is enclosed in parentheses The first constant is the real part and the second is the imaginary part A complex constant COMPLEX 8 uses 8 bytes of storage FORTRAN 77 Language Reference May 2000 36 EX 16 is an ordered pair of real or integer EAL 8 and the other is INTEG ER REAL 4 Example Complex constants COMPLEX 16 Constants A double complex constant COMPLI constants where one of the constants is RI or REAL 8 The constants are separated by a comma and the pair is enclosed in parentheses The first constant is the real part and the second is the imaginary part A double EX 16 uses 16 bytes of storage complex constant COMPLI Example Double complex constants t 1 0 2 0D0 100 2 33 4 5126 Invalid need second par 1 0 2 0 Not DOUBLE COMPLEX need a REAL 8 9 01D6 603 COMPLEX 32 Quad Complex Constants SPARC only A quad complex constan
79. real number The double precision data type DOUBLE PRECISION which has the synonym REAL 8 holds one double precision datum The default size for DOUBLE PRECISION with no size specified is 8 bytes A DOUBLE PRECISION element has a sign bit an 11 bit exponent and a 52 bit fraction These DOUBLE PRECISION elements in f77 conform to the IEEE standard for double precision floating point data The layout is shown in Data Representations on page 365 Chapter 2 Data Types and Data Items 27 INTEGER The integer data type INTEGER holds a signed integer The default size for INTEGER with no size specified is 4 and is aligned on 4 byte boundaries However these defaults can be changed by compiling with certain special options see Size and Alignment of Data Types on page 31 INTEGER 2 The short integer data type INTEGER 2 holds a signed integer An expression involving only objects of type INTEGER 2 is of that type Using this feature may have adverse performance implications and is not recommended Generic functions return short or long integers depending on the default integer type If a procedure is compiled with the i2 flag all integer constants that fit and ER no explicit size are of type INTEGER 2 If the all variables of type INTEG precision of an integer valued intrinsic function is not determi
80. same program unit as the GO TO statement The same statement label can appear more than once in a GO TO statement The statement control jumps to must be executable not DATA ENTRY FORMAT or INCLUDE Control cannot jump into a DO IF ELSE IF or ELSE block from outside the block FORTRAN 77 Language Reference May 2000 164 Example Example Assigned 60 TO ASSIGN 10 TO GO TO 10 20 30 40 10 CONTINUE 40 STOP Chapter4 Statements 165 GO TO Computed The computed GO TO statement selects one statement label from a list depending on the value of an integer or real expression and transfers control to the selected one GO TO s s e Parameter Description 5 Statement label of an executable statement e Expression of type integer or real Description Execution proceeds as follows e is evaluated first It is converted to integer if required If 1 gt e lt n where n is the number of statement labels specified then the eth label is selected from the specified list and control is transferred to it If the value of e is outside the range that is e gt 1 or e gt n then the computed GO TO statement serves as a CONTINUE statement Restrictions s must be in the same program unit as the GO TO statement The same statement label can appear more than once in a GO TO statement The stat
81. scratch file Use INQUIRE if you want to reopen it later Changing I O Initialization with IOINIT Traditional FORTRAN environments usually assume carriage control on all logical units They usually interpret blank spaces on input as zeroes and often provide attachment of global file names to logical units at runtime The routine IOINIT 3F can be called to specify these I O control parameters This routine m Recognizes carriage control for all formatted files Ignores trailing and embedded blanks in input files Positions files at the beginning or end upon opening m Preattaches file names of a specified pattern with logical units 268 FORTRAN 77 Language Reference May 2000 Example IOINIT and logical unit preattachment CALL IOINIT TRUE FALSE FALSE FORT FALSE For the above call the FORTRAN runtime system looks in the environment for names of the form FORTnn and then opens the corresponding logical unit for sequential formatted I O With the above example suppose your program opened unit 7 as follows OPEN UNIT 07 FORM FORMATTED The FORTRAN runtime system looks in the environment for the FORTO7 file and connects it to unit 7 In general names must be of the form PREFIXnn where the particular PREFIX is specified in the call to IOINIT and nn is the logical unit to be opened Unit numbers less than 10 must include the leading
82. structures STRUCTURE structure name field list field declaration field declaration END STRUCTURE Each field declaration can be one of the following a A substructure either another structure declaration or a record that has been previously defined a A union declaration A type declaration which can include initial values Description A STRUCTURE statement defines a form for a record by specifying the name type size and order of the fields that constitute the record Optionally it can specify the initial values A structure is a template for a record The name of the structure is included in the STRUCTURE statement and once a structure is thus defined and named it can be used in a RECORD statement The record is a generalization of the variable or array where a variable or array has a type the record has a structure Where all the elements of an array must be of the same type the fields of a record can be of different types Structures fields and records are described in Structures on page 56 Restrictions The name is enclosed in slashes and is optional in nested structures only If slashes are present a name must be present 244 FORTRAN 77 Language Reference May 2000 You can specify the field list within nested structures only There must be at least one field declaration Each structure name must be unique among structures although you can use struct
83. this way but not Control A Control B Control C or Control J Example A valid way to enter a Control C CHARACTER etx etx CHAR 3 Multiple byte characters Multiple byte characters such as Kanji are allowed in comments and strings Character String Assignment The form of the character string assignment is v e e Expression giving the value to be assigned v Variable array element substring or character record field The meaning of character assignment is to copy characters from the right to the left side Execution of a character assignment statement causes evaluation of the character expression and assignment of the resulting value to v Chapter 3 Expressions 7 Ife is longer than characters on the right are truncated Ife is shorter than blank characters are padded on the right Example The following program below displays joinedAA CHARACTER A 4 B 2 C 8 A join B ed C A B PRINT C END Also this program displays the equa1 string IF tabt cd EQ abcd PRINT eq al END Example Character assignment CHARACTER BELL 1 C2 2 C3 3 C5 5 C6 6 REAL 2 02 a C3 uvwxyz 05 vwxyz 1 05 61 2 C6 05 C2 1 abcd Z wxyz BELL CHAR 7 Control Character G The results are Variable Receiving Value Comment C2 IZA A trailing blank C3 uvw C5 ABxyz
84. to read or write For each read you still must tell it the initial record to start at in this case which byte so you must know the size of each item A simple example follows FORTRAN 77 Language Reference May 2000 308 2 9 Example Direct access create 3 records with 2 integers each y 8 demo cat Direct1l f integer u 4 v 5 w 6 open 1 access DIRECT write 1 rec l u v write 1 rec 2 w x write 1 rec 3 y z end demo 77 silent Direct1 f demo a out demo Example Direct access read the 3 records demo cat 16062 5 integer u V W Y 2 open 1 access DIRECT read 1 rec 1 u v read 1 rec 2 w x read 1 rec 3 y 2 write u W X Y end demo f77 silent Direct2 f demo a out 4 5 6 7 8 9 demo Here we knew beforehand the size of the records on the file In this case we can read the file just as it was written However if we only know the size of each item but not the size of the records on a file we can use recl 1 on the OPEN statement to have the I O list itself determine Input and Output 309 Chapter 5 how many items to read Example Direct access read variable length records 0011 demo cat Direct3 f integer W 2 open 1 access DIRECT recl 1 read 1 rec l u v w read 1 rec 13 x y 2 write Yr
85. type statement Examples Example 1 Character integer and real scalars Real arrays CHARACTER TTL 16 REAL VEC 5 PAIR 2 DATA TTL Arbitrary Titles amp 9 N O amp PAIR 1 9 0 amp VEC 3 9 0 0 1 0 9 Example 2 Arrays implied Do REAL R 3 2 S 4 4 DATA S I I I 1 4 4 1 0 R I J J 1 3 I 1 2 6 1 0 Example 3 Mixing an integer and a character CHARACTER CR 1 INTEGER 1 2 N 4 DATA I 00 N 4Hs12t CR 13 120 FORTRAN 77 Language Reference May 2000 DECODE ENCODE ENCODE writes to a character variable array or array element DECODE reads from a character variable array or array element Data is edited according to the format identifier Similar functionality can be accomplished using internal files with formatted sequential WRITE statements and READ statements ENCODE and DECODE are not in the FORTRAN 77 Standard and are provided for compatibility with older versions of FORTRAN CODE size f buf IOSTAT ios ERR s iolist DECODE size f buf IOSTAT ios ERR S iolist Parameter Description size Number of characters to be translated an integer expression f Format identifier either the label of a FORMAT statement or a character expression specifying the format string or an asterisk buf Variable array or array element ios I
86. used The default size for a declaration such as LOGICAL zZ can be altered by compiling with any of the options dbl i2 r8 or xt ypemap See the discussion in Chapter 2 for details LOGICAL 1 For a declaration such as LOGICAL 1 H the variable H is always an BYTE element in memory interpreted as a single logical value LOGICAL 2 For a declaration such as LOGICAL 2 H the variable H is always an INTEGER 2 element in memory interpreted as a single logical value LOGICAL 4 For a declaration such as LOGICAL 4 H the variable H is always an INTEGER 4 element in memory interpreted as a single logical value LOGICAL 8 For a declaration such as LOGICAL 8 H the variable H is always an INTEGER 8 element in memory interpreted as a single logical value FORTRAN 77 Language Reference May 2000 192 193 X 4 2 Statements Chapter 4 Examples Example 1 Each of these declarations are equivalent LOGICAL U V 9 LOGICAL 4 U V 9 LOGICAL U 4 V 9 4 Example 2 Initialize LOGICAL U false V 0 W 4 true MAP The MAP declaration defines alternate groups of fields in a union MAP field declaration ffeld declaration END MAP Description Each field declaration can be one of the following m Type declaration which can include initial values Substructure either another structure de
87. you have come to expect from Sun the only thing that has changed is the name We believe that the Forte name blends the traditional quality and focus of Sun s core programming tools with the multi platform business application deployment focus of the Forte tools such as Forte Fusion and Forte for Java The new Forte organization delivers a complete array of tools for end to end application development and deployment For users of the Sun WorkShop tools the following is a simple mapping of the old product names in WorkShop 5 0 to the new names in Forte Developer 6 Old Product Name New Product Name Sun Visual WorkShop C Forte C Enterprise Edition 6 Sun Visual WorkShop C Personal Forte C Personal Edition 6 Edition Sun Performance WorkShop Fortran Forte for High Performance Computing 6 Sun Performance WorkShop Fortran Forte Fortran Desktop Edition 6 Personal Edition Sun WorkShop Professional C Forte C 6 Sun WorkShop University Edition Forte Developer University Edition 6 In addition to the name changes there have been major changes to two of the products Forte for High Performance Computing contains all the tools formerly found in Sun Performance WorkShop Fortran and now includes the C compiler so High Performance Computing users need to purchase only one product for all their development needs Forte Fortran Desktop Edition is identical to the former
88. 0 In the above example a structure named PRODUCT is defined to consist of the five fields ID NAME MODEL COST and PRICE For an example with a field list see Structure Within a Structure on page 61 Rules and Restrictions for Structures Note the following The name is enclosed in slashes and is optional only in nested structures If slashes are present a name must be present You can specify the field list within nested structures only There must be at least one field declaration Each structure name must be unique among structures although you can use structure names for fields in other structures or as variable names The only statements allowed between the STRUCTURE statement and the END STRUCTURE statement are field declaration statements and PARAMETER statements A PARAMETER statement inside a structure declaration block is equivalent to one outside Rules and Restrictions for Fields Fields that are type declarations use the identical syntax of normal FORTRAN type statements All 77 types are allowed subject to the following rules and restrictions Any dimensioning needed must be in the type statement The DIMENSION statement has no effect on field names You can specify the pseudo name FILL for a field name FILL is provided for compatibility with other versions of FORTRAN It is not needed in 77 because the alignment problems are taken care of
89. 00 Most Significant Least significant The bits are numbered the same on these systems even though the bytes are numbered differently Following are some possible problem areas Passing binary data over the network Use External Data Representation XDR format or another standard network format to avoid problems Porting raster graphics images between architectures If your program uses graphics images in binary form and they have byte ordering that is not the same as for images produced by SPARC system routines you must convert them If you convert character to integer or integer to character between architectures you should use XDR If you read binary data created on an architecture with a different byte order then you must filter it to correct the byte order See also the xdr 3N man page 370 FORTRAN 77 Language Reference May 2000 APPENDIX D VMS Language Extensions This chapter describes the VMS language extensions that Sun WorkShop Fortran 77 supports These extensions are all of course nonstandard Background This FORTRAN compiler includes the VMS extensions to make it as easy as possible to port FORTRAN programs from VMS environments to Solaris environments The compiler provides almost complete compatibility with VMS FORTRAN These extensions are included in dbx as well as 77 VMS Language Features in Sun Fortran This list is a summary of the VMS features that are included
90. 000000000000 0 80000000 8000000000000000 1 0 3F800000 3FF0000000000000 1 0 BF800000 BFF0000000000000 2 0 40000000 4000000000000000 0 40400000 4008000000000000 Infinity 7F800000 7FF0000000000000 Infinity FF800000 FFF0000000000000 NaN 7EXXXXXX 7 FEXXXXXXXXXXXXX Arithmetic Operations on Extreme Values This section describes the results of basic arithmetic operations with extreme and ordinary values We assume all inputs are positive and no traps overflow underflow or other exceptions happen TABLE 0 3 Extreme Value Abbreviations Abbreviation Meaning Sub Subnormal number Num Normalized number Appendix C Data Representations 367 NaN NaN NaN NaN NaN NaN NaN NaN NaN NaN NaN NaN TABLE 0 3 Extreme Value Abbreviations Continued Abbreviation Meaning Inf Infinity positive or negative NaN Not a Number Uno Unordered TABLEC 4 Extreme Values Addition and Subtraction Right Operand Left Operand 0 Sub Num Inf 0 0 Sub Num Inf Sub Sub Sub Num Inf Num Num Num Num Inf Inf Inf Inf Inf Note NaN NaN NaN NaN NaN Note Inf Inf and Inf Inf Inf Inf Inf NaN TABLEC 5 Extreme Values Multiplication Right Operand Left Operand 0 Sub Num Inf 0 0 0 0 NaN Sub 0 0 NS Inf Num 0 NS Num Inf Inf NaN Inf Inf Inf NaN NaN NaN NaN NaN 368 FORTRAN 77 Language Reference May 2000 In the above table NS means either Num or Sub result possible NaN NaN NaN
91. 1 172 173 174 175 176 177 Dec 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 Name lt 5 77000 9 0 G AH 0 0 0 2 65 YS Hex 40 41 42 43 44 45 46 47 48 49 4A 4B 4C 4F 50 51 52 53 54 55 56 57 58 59 5A 5B 5C 5F Oct 100 101 102 103 104 105 106 107 110 TEL 112 113 114 TLS 116 117 120 TZI 122 123 124 125 126 124 130 131 132 133 134 135 136 t37 Dec 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 ASCII Character Set Hex 20 SP 21 22 23 24 25 26 27 28 29 2A 2 2 2 2 2F 30 341 32 33 34 35 36 3 7 38 39 3A 3 3C 3 3 Ra PNH DAO RAR 600 9 7620 0041 A xe ee wy V 5 OQ bh DB DB WB WBA WwW OA 039 0 OO 00 6 6 6 A 3 60 41 0039000 65 6 6 OO 6 6 Or E gt SE D E e 6 6 CO CO 65 65 6 6 O OO OO CO 6 OC 6 6 5 DNA AD OO OU WN o gt 4 1 1 1 4 4 4 1 6 OB WNEHF OC Dec 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
92. 13 4 END The above program displays A1234 678 gt AAAA1 234 6780 In the above example F8 4 does not allow for the sign F13 4 results in four leading blanks and one trailing zero G Editing The G specifier is for decimal real data items The general forms are G w d or Gw dEe The D E F and G edit specifiers interpret data in the same way The representation for output by the G edit descriptor depends on the magnitude of the internal datum In the following table N is the magnitude of the internal datum Range Form 0 1SN lt 1 0 F w 4 d 1 0 lt N lt 10 0 F w 4 d 1 104 2 gt lt 104 F w 4 1 104 gt 101 F w 4 0 Chapter5 Input and Output 299 Commas in Formatted Input If you are entering numeric data that is controlled by a fixed column format then you can use commas to override any exacting column restrictions Example Format 110 F20 10 14 Using the above format reads the following record correctly 345 05e 3 12 The I O system is just being more lenient than described in the FORTRAN Standard In general when doing a formatted read of noncharacter variables commas override field lengths More precisely for the Iw Fw d Ew d Ee and Gw d input fields the field ends when w characters have been scanned or a comma has been scanned whichever occurs first If it is a comma the fie
93. 1539 1980 as well as standards FIPS 69 1 BS 6832 and MIL STD 1753 This is no longer the current Fortran standard Floating point arithmetic for both compilers is based on IEEE standard 754 1985 and international standard IEC 60559 1989 m On SPARC platforms both compilers provide support for the optimization exploiting features of SPARC V8 and SPARC V9 including the UltrasPARC implementation These features are defined in the SPARC Architecture Manuals Version 8 ISBN 0 13 825001 4 and Version 9 ISBN 0 13 099227 5 published by Prentice Hall for SPARC International In this document Standard means conforming to the versions of the standards listed above Non standard or Extension refers to features that go beyond these versions of these standards The responsible standards bodies may revise these standards from time to time The versions of the applicable standards to which these compilers conform may be revised or replaced resulting in features in future releases of the Fortran compilers that create incompatibilities with earlier releases Extensions Extensions to the standard FORTRAN 77 language include recursion pointers double precision complex quadruple precision real quadruple precision complex and many VAX and VMS FORTRAN 5 0 extensions including NAMELIST DO WHILE structures records unions maps and variable formats Multiprocessor FORTRAN includes automatic and explicit loop
94. 2 TEGER 4 TEGER 2 TEGER 4 TEGER 2 TEGER 4 gt D Dee i gt EA A A g TABLE 6 10 VMS Degree Based Trigonometric Functions Continued Generic Specific Name Names Function Argument Type ACOSD Arc cosine ACOSD REAL 4 DACOSD REAL 8 QACOSD REAL 16 ATAND Arc tangent ATAND REAL 4 DATAND REAL 8 QATAND REAL 16 ATAN2D Arc tangent of al a2 ATAN2D REAL 4 DATAN2D REAL 8 QATAN2D REAL 16 VMS Bit Manipulation TABLE 6 11 VMS Bit Manipulation Functions Specific Names Function Argument Type From a1 initial bit a2 extract a3 bits 175 INTEGER 2 JIBITS INTEGER 4 Shift 81 logically by a2 bits if a2 positive shift left if a2 negative shift right IISHFT Shift 81 logically left by a2 bits INTEGER 2 JISHFT Shift a1 logically left by a2 bits INTEGER 4 In al circular shift by a2 places of right a3 bits LISHE TC INTEGER 2 JISHETC INTEGER 4 Bitwise AND of al a2 IIAND INTEGER 2 JIAND INTEGER 4 Bitwise OR of al a2 IIOR INTEGER 2 JIOR INTEGER 4 Generic Name IBITS ISHFT ISHFTC IAND IOR FORTRAN 77 Language Reference May 2000 346 347 Result Type EGER 2 EGER 4 INTEGER 2 INTEGER 4 INTEGE
95. 29 002 Invalid comma not allowed error message 2147483647 2147483648 Invalid too large error message 38 FORTRAN 77 Language Reference May 2000 Alternate Octal Notation You can also specify integer constants with the following alternate octal notation Precede an integer string with a double quote and compile with the 1 option These are octal constants of type INTEGER Example The following two statements are equivalent You can also specify typeless constants as binary octal hexadecimal or Hollerith See Typeless Constants Binary Octal Hexadecimal on page 43 Long Integers Compiling with an option that promotes the range from INTEGER 4 21474836 21474836 to INTEGER 8 9223372036854775808 9223372036854775807 The integer constant is stored or passed as an 8 byte integer data type INTEGER 8 Short Integers If a constant argument is in the range 32768 32767 it is usually widened to a 4 byte integer data type INTEGER 4 but compiling with the i2 option will cause it to be stored or passed as a 2 byte integer data type INTEGER 2 Logical Constants A logical constant is either the logical value true or false The only logical constants are TRUE and FALSE no others are possible The period delimiters are necessary A logical constant takes 4 bytes of storage If it is an actual argument it is
96. 296 298 299 284 286 P 302 positional 289 Q 300 S 303 SP 303 ss 303 SU 303 T 289 X 289 SE 137 SSE IF 139 mbedded comments 372 empty spaces in structures 58 245 ENCODE 121 141 x x X x x 9 es x oO format 279 304 304 A 281 B 278 BN 278 BZ 278 D 294 defaults for field descriptors 276 E 296 F 298 G 299 I 284 L 286 O 287 of source line 17 P 302 Q 300 R 294 read into hollerith edit descriptor 284 s 303 SP 303 specifier 372 SS 303 standard fixed 17 SU 303 tab 18 variable expressions 159 160 vertical control 279 X 289 Z 287 format specifier 293 formats 305 runtime 217 222 258 284 5 variable format expressions 307 formatted I O 273 output 267 formatted I O 273 forms of I O 265 FORTRAN list of statements 17 Fortran 95 style constants 46 free 66 338 FUNCTION 161 extreme exponent data representation 366 values for arithmetic operations 367 F F format specifier 298 field 56 argument that is a field 58 230 COMMON with a field 58 230 declaration 56 194 244 DIMENSION with a field 58 230 dimensioning in type statements 57 245 EQUIVALENCE not allowed in 58 231 list 57 list of a structure 56 245 map with a field 62 253 name FILL 58 245 NAMELIST not allowed in 58 231 offset 58 245 reference 59 SAVE no
97. 329 DBLEQ 329 DCMPLX 330 deallocate memory by free 66 debug statement 377 decimal point in octal or hex input 288 declaration field 56 194 244 initialize in 372 map 62 253 record 58 230 structure 56 union 62 DECODE 121 default inquire options 182 delimiter character constant 319 NAMELIST or amp 319 DFLOAT 329 DIMENSION 123 dimension arrays 49 direct I O 270 I O record specifier 222 271 374 DIRECT option for ACCESS in OPEN file 199 directives general 19 parallelization 20 DISPOSE option for CLOSE 374 DO 126 DO WHILE 131 DOALL directive 21 dollar sign edit descriptor 279 in names 14 NAMELIST delimiter 319 DOSERIAL directive 21 DOUBLE COMPLEX 27 134 double precision real 41 fortran 95 style 46 hex 43 integer 38 logical 39 octal 43 quad complex 37 quad real 42 real 39 REAL 16 42 REAL 4 40 REAL 8 41 typeless 43 continuation lines 17 18 CONTINUE 117 control characters 14 44 77 in assignment 79 95 meanings 353 D dcomments 19 D format specifier 294 DATA 118 data namelist syntax 319 322 representation double precision 365 real number 365 signed infinity 366 type BYTE 25 CHARACTER 26 COMPLEX 26 COMPLEX 16 27 COMP LEX 32 27 COMP LEX 8 27 DOUBLE COMPLEX 27 27 DOUBLE PRECISION 27 INTEGER 28 INTEGER 4 28 LOGICAL 29 LOGICAL 1 25 29 LOGICAL 2 29
98. 4 Statements 107 Examples Example 1 Character strings and arrays of character strings CHARACTER 17 A B 3 4 V 9 CHARACTER 6 3 C The above code is exactly equivalent to the following CHARACTER A 17 B 3 4 17 V 9 17 CHARACTER C 6 3 Both of the above two examples are equivalent to the nonstandard variation CHARACTER A 17 B 17 3 4 V 17 9 nonstandard There are no null zero length character string variables A one byte character string assigned a null constant has the length zero Example 2 No null character string variables CHARACTER S 1 During execution of the assignment statement the variable 5 is precleared to blank and then zero characters are moved into S so S contains one blank because of the declaration the intrinsic function LEN S will return a length of 1 You cannot declare a size of less than 1 so this is the smallest length string variable you can get Example 3 Dummy argument character string with constant length SUBROUTINE SWAN A CHARACTER A 32 Example 4 Dummy argument character string with length the same as corresponding actual argument SUBROUTINE SWAN A CHARACTER A FORTRAN 77 Language Reference May 2000 108 Example 5 Symbolic constant with parenthesized asterisk CHARACTER INODE
99. 5 Compare to IF Block Compare to DO Compare to MAP Compare to STRUCTURE Compare to UNION Sample Statements Appendix B ERR 9 v v A Dy 2 SION A D 1 2D3 Y 2 IOSTAT I1 Y A2 4 A 1 1 A P D Q FEE 0D0 ODO V 1 X V 10 TABLE B 1 Name Examples DOUBLE COMPLEX DOUBLE COMPLEX U DOUBLE COMPLEX U COMPLEX U 1 0 1 v 1 0 1 DOUBLE PRECISION DOUBLE PRECISION ENDFIL UNIT I ENDFILE I ENDFILE UNIT U END IF END MAP END STRUCTURE END UNION ENTRY SCHLEP X ENTRY SCHLEP Al ENTRY SCHLEP EQUIVALENCE EQUIVALENCE V EQUIVALENCE EXTERNAL RNGKTA ELSE END DO ENDFILE END IF END MAP END STRUCTURE END UNION ENTRY EQUIVALENCE EXTERNAL TABLE 8 1 FORTRAN Statement Samples Continued Name Examples Comments FORMAT 10 FORMAT 2X 213 3F6 1 4E12 2 2A6 3L2 LO FORMAT 2D6 1 3G12 2 LO FORMAT 213 3 3G6 1E3 4E12 2E3 LO FORMAT a quoted string Strings another I2 LO FORMAT 18Hhollerith string I2 Hollerith 10 FORMAT 1X T10 Al T20 Al Tabs 10 FORMAT 5X TR10 Al TR10 A1 TL5 A1 Tab right left 10 PORMAT Init 12 3X i Last I2 10 FORMAT 1X Enter path name 5 10 FORMAT 84 2 Q 80 Al 0 10 FORMAT Octal 06
100. 6 data type 26 statement 114 COMPLEX 16 27 37 COMP LEX 32 27 37 COMPLEX 8 27 computed GO TO 166 concatenation of strings 76 operator 76 conditional termination control 304 consecutive commas NAMELIST 321 operators 373 constant expression 83 names symbolic constants 14 null character constants 34 octal 373 radix 50 372 signed 34 typeless numeric 373 unsigned 34 values in NAMELIST 320 constants 33 binary 43 characters 34 complex 36 COMPLEX 16 37 COMPLEX 32 37 double complex 37 Index 3 C c comments 19 directive 19 CALL 103 carriage control 266 279 279 all files 268 blank 0 1 279 first character 279 space 0 1 279 carriage return edit descriptor 279 case 14 15 CHAR 95 330 CHARACTER data type 26 statement 107 character array 49 assignment 77 78 79 95 boundary 31 concatenate 76 constant delimiter 319 NAMELIST 320 constants 34 declared length 109 declaring the length 108 dummy argument 108 editing 281 expression 76 format specifier 372 functions 335 join 76 null constants 34 operator 76 packing 107 set 12 strings 108 substring 54 valid characters in names 14 characters special 13 CLOSE 110 CMPLX 330 colon array bounds 49 edit descriptor 304 quad real 0 REAL 30 REAL 16 30 REAL 4 30 REAL 8 30 short integer 28 data types and data structures 23 DBLE
101. 6 REAL 16 REAL 4 REAL 4 REAL 8 REAL 8 REAL 16 REAL 16 REAL 4 REAL 4 REAL 4 REA 4 READ 4 READ 4 Intrinsic Functions 349 5 sign a 5 sign a 5 sign a Nearest integer INT a 5 sign a 5 sign a 5 sign a Function Truncation toward zero Truncation toward zero Truncation toward zero Truncation toward zero Truncation toward zero Truncation toward zero Truncation toward zero Nearest integer INT at Nearest integer INT at Nearest integer INT at Nearest integer INT at Nearest integer INT at Fix Fix Maximum of two or more arguments Maximum of two or more arguments Minimum of two or more arguments Minimum of two or more arguments Chapter 6 Specific Names FEINT JINT LINT IIDINT JIDINT IIQINT IQINT IIDNNT JIDNNT IIQNNT IQNNT IIFIX JIFIX IMAX1 a a2 JMAX1 a a2 IMINI1 a a2 JMIN1 a a2 ININT J U J J U J U J Functions Translated to a Generic Name In some cases each VMS specific name is translated into an 77 generic name TABLE 6 14 VMS Functions That Are Translated into 77 Generic Names Result Type 4 4 8 8 4 4 4 4
102. 6 promote types 72 prompt for namelist names 322 properties file 180 Q Q edit descriptor 300 QCMPLX 330 QEXT 329 QEXTD 329 QFLOAT 329 QREAL 329 quad complex 27 complex constants 37 exponent 42 real constants 42 real data type 30 FORM 200 IOSTAT 201 RECL 200 STATUS 201 UNIT 198 OPEN options 374 print file 266 statement 197 202 open files limit of 263 operand 69 operator 69 70 concatenate string 76 substring 54 character 76 concatenation 76 precedence 71 relational 82 two consecutive operators 72 373 with extreme values 367 optimization problems with pointers 67 option DISPOSE for CLOSE 374 e 18 i2 short integer 28 long lines 18 NAME for OPEN 374 number of continuation lines 18 OPTIONS 205 order bit and byte 369 P P edit descriptor 302 packing character 107 padding 19 PARAMETER nonstandard alternate 375 377 statement 57 207 245 parameter name 14 PATH environment variable 1 PAUSE 210 permissions ACCESS in INQUIRE 180 pointee 212 390 FORTRAN 77 Language Reference May 2000 statement 8 STATIC not allowed in 231 variable length 200 recursive 96 162 240 reference field 59 record 59 relational operator 82 release memory by free 66 repeat NAMELIST 321 representation of data 365 requesting namelist names 322 restrictions field
103. 61 62 63 TABLE A 1 Name DEL DC2 DC3 Dc4 AK SYN ETB CAN EM SUB ESC FS GS RS US Hex 00 01 02 03 04 05 06 07 08 09 OA w Z 0002 9 lt lt Oct 000 001 002 003 004 005 006 007 OD O Or T No FF WN EF 020 021 022 023 024 025 026 027 030 031 032 033 034 035 036 037 FORTRAN 77 Language Reference May 2000 O01 Oy 5 NEN Oo 0 WWNHNNNNNNNNNKFPHPPHPBPBPHP BP HEP 0 5090 41 0 352 TABLE A 2 Control Characters Control Key s Shift and Control Keys Dec Oct Hex Name Keys Meaning 0 000 00 NUL s P Null or time fill character 1 001 01 SOH A Start of heading 2 002 02 STX B Start of text 3 003 03 ETX NG End of text EOM 4 004 04 EOT 4D End of transmission 5 005 05 ENQ E Enquiry WRU 6 006 06 ACK AF Acknowledge RU 7 007 07 BEL G Bell 8 010 08 BS H Backspace 9 011 09 HT I Horizontal tab 10 012 OA LF 9 Line feed newline 11 013 0B VT K Vertical tab 12 014 oc FF AL Form Feed 13 015 OD CR 5 Carriage Return 14 016 OE SO N Shift Out 15 017 OF SI SG Shift In 16 020 LO DLE 5 Data link escape 17 021 L1 DC1 yO Device control 1 X ON 18 022 L2 DC2 oR Device control 2 TAPE 19 023 3 DES NS Device control 3 X OFF 20 024 L4 DC4 AF Device control 4 TAPE 21 025 L5 NAK U Negative acknowledge
104. 80 unit preattached 269 units 263 LOGICAL 1 29 UNFORMATTED 184 UNIT 184 INT 329 INTEGER 28 186 integer and logical 74 constants 38 editing 284 functions 348 logical mixed expressions 73 operand with logical operator 74 short 39 INTEGER 2 28 INTEGER 4 28 INTEGER 8 28 internal files 272 INTRINSIC 189 intrinsic functions 325 344 arithmetic 327 character 335 environmental inquiry 337 mathematical 333 memory allocation and deallocation 338 special VMS 374 trigonometric 331 type conversions 329 invalid characters for data 14 ioinit 269 IOSTAT OPEN specifier 201 IQINT 329 ishift 343 ISO 1539 1980 FORTRAN standard 11 J join strings 76 K key word 12 kind type parameter in constants 46 388 FORTRAN 77 Language Reference May 2000 data syntax 320 END 319 I O 315 negative values hex and octal output 289 nested substructure 60 newline character 36 77 NML 318 noncharacter runtime format specifier 372 none implicit data typing 372 nonexecutable statements 16 nonstandard PARAMETER 375 377 notation octal alternate 39 null character 36 character constants 34 data item NAMELIST 321 number of continuation lines 18 open files 263 numeric constant typeless 373 0 0 constant indicator 43 edit descriptor 287 octal alternate notation 39 constant 373 constants 43 initializat
105. 82 Not REAL need decimal point or exponent 29 002 0 Invalid comma not allowed error message 1 6E39 Invalid too large machine infinity is used 1 9 Invalid too small some precision is lost The restrictions are m Other than the optional plus or minus sign a decimal point the digits 0 through 9 and the letter E no other characters are allowed The magnitude of a normalized single precision floating point value must be in the approximate range 1 175494E 38 3 402823E 38 REAL 8 Double Precision Real Constants A double precision constant is an approximation of a real number It can be positive negative or zero If no sign is present the constant is assumed to be nonnegative A double precision constant has a double precision exponent and an optional decimal point Double precision constants REAL 8 use 8 bytes of storage The REAL 8 notation is nonstandard Double Precision Exponent A double precision exponent consists of the letter D followed by an optional plus or minus sign followed by an integer A double precision exponent denotes a power of 10 The value of a double precision constant is the product of that power of 10 and the constant that precedes the D The form and interpretation are the same as for a real exponent except that a D is used instead of an E Chapter 2 Data Types and Data Items 1 Examples of double precision constants are 1 6D 9 7D3 1 0D2 0 Invalid
106. A to 5 ora tof Outside of DATA statements such constants are treated as the type required by the context If a typeless constant is used with a binary operator it gets the data type of the other operand 8 0 37 O In DATA statements such constants are treated as typeless binary hexadecimal or octal constants Hollerith Constants A Hollerith constant consists of an unsigned nonzero integer constant followed by the letter H followed by a string of printable characters where the integer constant designates the number of characters in the string including any spaces and tabs A Hollerith constant occupies 1 byte of storage for each character Chapter 2 Data Types and Data Items 5 A Hollerith constant is aligned on 2 byte boundaries The FORTRAN standard does not have this old Hollerith notation although the standard recommends implementing the Hollerith feature to improve compatibility with old programs Hollerith data can be used in place of character string constants They can also be used in IF tests and to initialize noncharacter variables in DATA statements and assignment statements though none of these are recommended and none are standard These are typeless constants Example Typeless constants CHARACTER C 1 CODE 2 INTEGER TAG 2 DATA TAG 2Hok COD 2Hno IF Q Il EQ 1HZ CALL PUNT The rules and restrictions on Hollerith constants are The number of charac
107. ABLE 0 1 Floating point Representation Single Double Quadruple Sign Bit 31 Bit 63 Bit 127 Exponent Bits 30 23 Bits 62 52 Bits 126 112 Bias 127 Bias 1023 Bias 16583 Fraction Bits 22 0 Bits 51 0 Bits 111 0 Range approx 3 402823e 38 1 797693e 308 3 362E 4932 1 175494e 38 2 225074e 308 1 20E 4932 365 Extreme Exponents The representations of extreme exponents are as follows Zero signed Zero signed is represented by an exponent of zero and a fraction of zero Subnormal Number The form of a subnormal number is 1 sign gt 2 1 bias 0 where f is the bits in the significand Signed Infinity Signed infinity that is affine infinity is represented by the largest value that the exponent can assume all ones and a zero fraction Not a Number NaN Not a Number NaN is represented by the largest value that the exponent can assume all ones and a nonzero fraction Normalized REAL and DOUBLE PRECISION numbers have an implicit leading bit that provides one more bit of precision than is stored in memory For example IEEE double precision provides 53 bits of precision 52 bits stored in the fraction plus the implicit leading 1 FORTRAN 77 Language Reference May 2000 366 IEEE Representation of Selected Numbers The values here are as shown by dbx in hexadecimal TABLE 0 2 IEEE Representation of Selected Numbers Value Single Precision Double Precision 0 00000000 0000
108. AL 1 The one byte logical data type LOGICAL 1 which has the synonym BYTE can hold any of the following m One character m An integer between 128 and 127 The logical values TRUE or FALSE The value is as defined for LOGICAL but it can hold a character or small integer An example LOGICAL 1 Bit3 8 C1 Counter 0 Switch FALSE A LOGICAL 1 item occupies one byte of storage LOGICAL 1 is aligned on one byte boundaries LOGICAL 2 The data type LOGICAL 2 holds logical value TRUE or FALSE The value is defined as for LOGICAL A LOGICAL 2 occupies 2 bytes LOGICAL 2 is aligned on 2 byte boundaries LOGICAL 4 The The logical data type LOGICAL 4 holds a logical value TRUE or FALS value is defined as for LOGICAL A LOGICAL 4 occupies 4 bytes Chapter 2 Data Types and Data Items 9 LOGICAL 4 is aligned on 4 byte boundaries LOGICAL 8 The logical data type LOGICAL 8 holds the logical value TRUE or FALSE The value is defined the same way as for the LOGICAL data type A LOGICAL 8 occupies 8 bytes LOGICAL 8 is aligned on 8 byte boundaries REAL A real datum is an approximation of a real number The real data type REAL which usually has the synonym REAL 4 holds one real datum The usual default size for a REAL item with no size specified is 4 bytes and is aligned on 4 byte boundaries
109. AL A 3 5 L M N B N 1 2 N These arrays are dummy args REAL C N 1 2 N This array is local The restrictions are m The size of an adjustable array cannot exceed the size of the corresponding actual argument In the first caller of the call sequence the corresponding array must be dimensioned with constants m You cannot declare an adjustable array in COMMON If the array is local to the routine memory is allocated on entry to the routine and deallocated on return to 16 Assumed Size Arrays An assumed size array is an array that is a dummy argument and which has an asterisk as the upper bound of the last dimension 50 FORTRAN 77 Language Reference May 2000 You can declare assumed size arrays in the usual DIMENSION COMMON or type statements The following 77 extensions allow you to m declare assumed size arrays in a RECORD statement if that RECORD statement is not inside a structure declaration block m use an assumed size array as a unit identifier for an internal file in an I O statement m use an assumed size array as a runtime format specifier in an I O statement Example Assumed size with the upper bound of the last dimension an asterisk UTINE PULLDOWN EGER A 5 An assumed size array cannot be used in an I O list Array Names with No Subscripts An array name with no subscripts indicates the entire array It can appear in any of the follow
110. AX1 AX1 AX1 AX1 IN INO INO IMINO JMINO INO INO IN1 SNGL SNGLQ REAL DREAL DBLE DBLEQ QEXT QEXTD QFLOAT CMPLX DCMPLX ICHAR IACHAR ACHAR CHAR MAX MAX0 AMAX0 JZEXT LOC NT AND LINT IAND JINT IIAND QINT JIAND IQINT OR JIQINT IOR FIX IIOR 8 IEOR JIFIX IIEOR DINT JIOR IDINT JIEOR JIDINT NOT FLOAT INOT FLOATI JNOT FLOATJ XOR DFLOAT LSHIFT DFLOTI RSHIFT DFLOTJ LRSHFT IZEXT FORTRAN 77 Language Reference May 2000 190 LOGICAL The LOGICAL statement specifies the type to be logical for a symbolic constant variable array function or dummy function Optionally it specifies array dimensions and initializes with values LOGICAL len v len c v len c Parameter Description v Name of a symbolic constant variable array array declarator function or dummy function len Either 1 2 4 or 8 the length in bytes of the symbolic constant variable array element or function 8 is allowed only if db1 is on 6 List of constants for the immediately preceding name Description The declarations can be LOGICAL LOGICAL 1 LOGICAL 2 LOGICAL 4 LOGICAL 8 Chapter4 Statements 191 LOGICAL For a declaration such as LOGICAL H the variable H is usually one INTEGER 4 element in memory interpreted as a single logical value Specifying the size is nonstandard If you do not specify the size a default size is
111. DASIN QASIN ASIND DASIND 8 QASIND ACOS DACOS QACOS Generic Name SIN SIND COS COSD TAN TAND ASIN ASIND ACOS Args 1 Trigonometric Functions TABLE 6 3 Definition sin a sin a cos a cos a tan a tan a arcsin a arcsin a arccos a Intrinsic Function Sine See Note 7 Sine degrees See Note 7 Cosine See Note 7 Cosine degrees See Note 7 Tangent See Note 7 Tangent degrees See Note 7 Arcsine See Note 7 Arcsine degrees See Note 7 Arccosine See Note 7 Function Type OUBLI Trigonometric Functions Continued Generic Specific Args Name Names Argument Type 1 ACOSD 5 ACOSD amp REAL DACOSD 8 DOUBLE QACOSD REAL 16 1 ATAN ATAN REAL DATA DOUBLE QATAN REAL 16 2 ATAN2 ATAN2 REAL DATAN2 DOUBLE QATAN2 REAL 16 1 ATAND 5 ATAND REAL DATAND DOUBLE QATAND REAL 16 2 ATAN2D ATAN2D REAL DATAN2D DOUBLE QATAN2D REAL 16 1 SINH SINH REAL DSINH DOUBLE QSINH REAL 16 1 COSH COSH REAL DCOSH DOUBLE QCOSH REAL 16 1 TANH TANH REAL DTANH DOUBLE QTANH REAL 16 TABL
112. Description a Name of an array a d Specifies the dimension of the array It is a list of 1 to 7 declarators separated by commas Description The VIRTUAL statement has the same form and effect as the DIM It is included for compatibility with older versions of FORTRAN Example VIRTUAL M 4 4 V 1000 END 4 Statements 255 Chapter VOLATILE The VOLATILE statement prevents optimization on the specified items VOLATILE nlist Parameter Description nlist List of variables arrays or common blocks Description The VOLATILE statement prevents optimization on the items in the list Programs relying on it are usually nonportable Example Example VOLATILE PROGRAM FFT INTEGER NODE 2 NSTEPS 2 REAL DELTA MAT 10 10 V 1000 X Z COMMON INI NODE DELTA V hb 2 VOLATILE 2 MAT INI EQUIVALENCE V In the above example the array V the variable 2 and the common block INI are explicitly specified as VOLATILE The variable X is VOLATILE through an equivalence 256 FORTRAN 77 Language Reference May 2000 WRITE The WRITE statement writes data from the list to a file Note For tape I O use the TOPEN routines WRITE UNIT FMT f IOSTAT ios REC rn ERR s iolist WRITE UNIT u NML grname IOSTAT ios
113. E LOGUNIT END FILE UNIT LOGUNIT Example 3 Error trap END FILE UNIT NOUT IOSTAT KODE ERR 9 9 WRITE Error at END FILE on unit NOUT STOP Chapter4 Statements 145 BND IF The END IF statement ends the block IF that the IF began and requires the following syntax END IF Description For each block IF statement there must be a corresponding END IF statement in the same program unit An END IF statement matches if it is at the same IF level as the block IF statement Examples Example 1 IF END IF Example 2 IF ELSE END IF 146 FORTRAN 77 Language Reference May 2000 END MAP The END MAP statement terminates the MAP declaration and requires the following syntax END MAP Description See UNION and MAP on page 253 for more information Restrictions The MAP statement must be within a UNION statement Example MAP CHARACTER 16 MAJOR END MAP Chapter4 Statements 147 BND STRUCTURE The END STRUCTURE statement terminates the STRUCTURE statement and requires the following syntax END STRUCTURI Description pm See STRUCTURE on page 244 for more information Example STRUCTURE PROD TEGER 4ID CHARACTER 16NAMI CHARACTER 8MODEL REAL 4COST REAL 4
114. E SAMPLE EW DELTA NAMELIST GRID ARRAY DELTA S 0 Zz 316 FORTRAN 77 Language Reference May 2000 In the above example DELTA is in the group CASE and in the group GRID Output Actions NAMELIST output uses a special form of WRITE statement which makes a report that shows the group name For each variable of the group it shows the name and current value in memory It formats each value according to the type of each variable and writes the report so that NAMELIST input can read it The syntax of NAMELIST WRITE is WRITE extu namelist specifier iostat err where namelist specifier has the form NML group name and group name has been previously defined in a NAMELIST statement The NAMELIST WRITE statement writes values of all variables in the group in the same order as in the NAMELIST statement Example NAMELIST output demo cat naml f naml f Namelist output CHARACTER 8 SAMPLE OGICAL 4 NEW REAL 4 DELTA NAMELIST CASE SAMPLE NEW DELTA DATA SAMPLE Demo NEW TRUE DELTA 0 1 WRITE CASE END demo 77 nam1 f 77 naml f naml f MAIN demo a out A amp case sample Demo new 1 delta 0 100000 A amp end demo Chapter5
115. E 6 3 Definition arccos a arctan a arctan al a2 arctan a arctan al a2 sinh a cosh a tanh a Intrinsic Function Arccosine degrees See Note 7 Arctangent See Note 7 Arctangent degrees See Note 7 Hyperbolic Sine See Note 7 Hyperbolic Cosine See Note 7 Hyperbolic Tangent See Note 7 332 FORTRAN 77 Language Reference May 2000 EX EX EX EX EX EX EX EX 333 Function Type REAL DOUBLE REAL 16 COMPLEX DOUBLE COMPL COMPLEX 32 OUBLI D 2 Pl rR lt x oO COMP LI DOUBLE COMP DOUBLE COMP COMP LEX 32 DOUBLI D z 2 Pl Fr x oO COMP LI DOUBLE COMP DOUBLE COMPL COMP LEX 32 DOUBLI sJ D 2 Pl Fr xX oO COMP LI DOUBLE COMP DOUBLE COMP COMP LEX 32 OUBLI J D E 2 Fr x oo COMP LI DOUBLE COMP DOUBLE COMP COMP LEX 32 Intrinsic Functions EX EX EX EX EX EX EX EX 6 Other Mathematical Functions Argument Type COMPLEX DO COMPL COMP LEX 32 G Ww COMP LEX DOUBLE COMPL COMP LEX 32 EAL DOUBLE R
116. EAL 16 COMP LEX DOUBLE COMP DOUBLE COMP COMP LEX 32 EAL DOUBLE REAL 16 COMP LEX DOUBLE COMP DOUBLE COMP COMP LEX 32 Chapter Other Mathematical Functions Specific Names AIMAG DIMAG QIMAG CONJG DCONJG QCONJG SQRT DSQRT QSQRT CSORT ZSQRT 0 COSQRT CBRT DCBRT QCBRT CCBRT ZCBRT CDCBRT COCBRT EXP EXP EXP EXP EXP EXP EXP O ANQODUP 0 YD TE hE EY S 10 O Q Generic Name IMAG CONJG SORT CBRT EXP LOG No of Args 1 TABLE 6 4 Intrinsic Function Definition Imaginary part 1 of a complex number ar ai a 1 2 a 1 3 e a log a See Note 6 Conjugate of a complex number See Note 6 Square root Cube root See Note 8 Exponential Natural logarithm Function Type 6 REAL DOUBLE REAL DOUBLE REAL DOUBLI REA Other Mathematical Functions Continued Argument Type DOUBLE Specific Names ALOG10 DLOG10 QLOG10 RFC DERFC TABLE 6 4 No of Generic Definition Args Name log10 a 1 LOG10 erf a 1 ERF 1 0 erf a
117. ECORD PRODUCT CURRENT PRIOR NEXT LINE 10 Each of the three variables CURRENT PRIOR and NEXT is a record which has the PRODUCT structure LINE is an array of 10 such records Note the following rules and restrictions for records m Each record is allocated separately in memory Initially records have undefined values unless explicitly initialized 58 FORTRAN 77 Language Reference May 2000 Records record fields record arrays and record array elements are allowed as arguments and dummy arguments When you pass records as arguments their fields must match in type order and dimension The record declarations in the calling and called procedures must match Within a union declaration the order of the map fields is not relevant See Unions and Maps on page 62 Record fields are not allowed in COMMON statements m Records and record fields are not allowed in DATA EQUIVALENCE or NAMELIST statements Record fields are not allowed in SAVE statements Record and Field Reference You can refer to a whole record or to an individual field in a record and since structures can be nested a field can itself be a structure so you can refer to fields within fields within fields and so forth The syntax of record and field reference is record name field name field name record name Name of a previously defined record variable field name Name of a
118. END demo 77 lis5 f Tissi MAIN demo a out 1 4 1 40000000 beauty 1 39999998 truth demo In the above example if you need accuracy specify the format Also note Output lines longer than 80 characters are avoided where possible Complex and double complex values include an appropriate comma Real double and quadruple precision values are formatted differently A backslash n n in a character string is output as a carriage return unless the x1 option is on and then it is output as a backslash n n Example List directed I O and backslash n with and without x1 demo cat 77 bslash f CHARACTER 5 8 12 n3 PRINT 5 END demo Chapter5 Input and Output 3 Without 1 n prints as a carriage return demo 77 silent bslash f demo a out 12 3 demo With 1 n prints as a character string demo 77 xl silent bslash f demo a out 12 n3 demo TABLE 5 8 Default Formats for List Directed Output Type Format BYTE Two blanks followed by the number CHARACTER n An n length of character expression COMP LEX AA 1PE14 5E2 1PE14 5E2 COMP LEX 16 AA 1PE22 13 E2 1PE22 13 E2 COMP LEX 32 AA 1PE44 34E3 1PE44 34E3 INTEGER 2 Two blanks followed by the number INTEGER 4 Two blanks followed by the number INTEGER 8 Two blanks followed by the number LOGICAL 1 Tw
119. EPT DOUBLE COMPLEX GOTO Assigned PRINT ASSIGN DOUBLE PRECISION GOTO Unconditional PRAGMA Assignment ELSE IF Arithmetic PROGRAM AUTOMATIC ELSE IF IF Block REAL BACKSPACE ENCODE IF Logical RECORD BLOCK DATA END IMPLICIT RETURN BYTE END DO INCLUDE REWIND CALL END FILE INQUIRE SAVE CHARACTER END IF INTEGER Statement Function CLOSE END MAP INTRINSIC STATIC COMMON END STRUCTURE LOGICAL STOP COMPLEX END UNION MAP STRUCTURE CONTINUE ENTRY AMELIST SUBROUTINE DATA EQUIVALENCE OPEN TYPE DECODE EXTERNAL OPTIONS UNION DIMENSION FORMAT PARAMETER VIRTUAL DO FUNCTION PAUSE VOLATILE DO WHILE GOTO POINTER WRITE The asterisk in the table indicates an executable statement Source Line Formats A statement takes one or more lines the first line is called the initial line the subsequent lines are called the continuation lines You can format a source line in either of two ways Standard fixed format Tab format 5 Standard Fixed Format The standard fixed format source lines are defined as follows The first 72 columns of each line are scanned See Extended Lines on page 18 The first five columns must be blank or contain a numeric label Continuation lines are identified by a nonblank nonzero in column 6 Short lines are padded to 72 characters Chapter 1 Elements of FORTRAN 17 m Long lines are truncated See Extended Lines on page 18 Tab Format The tab format sou
120. EX W the variable w 15 usually two REAL 4 elements contiguous in memory interpreted as a complex number If you do not specify the size a default size is used The default size for a declaration such as COMPLEX W can be altered by compiling with any of the options db1 28 xt ypemap See the discussion in Chapter 2 for details COMPLEX 8 For a declaration such as COMPLEX 8 W the variable W is always two REAL 4 elements contiguous in memory interpreted as a complex number COMPLEX 16 For a declaration such as COMPLEX 16 W Wis always two REAL 8 elements contiguous in memory interpreted as a double width complex number COMPLEX 32 SPARC only For a declaration such as COMPLEX 32_ Ww the variable W is always two REAL 16 elements contiguous in memory interpreted as a quadruple width complex number Comments There is a double complex version of each complex built in function Generally the specific function names begin with Z or CD instead of C except for the two functions DIMAG and DREAL which return a real value There are specific complex functions for quad precision SPARC only In general where there is a specific REAL a corresponding COMPLEX with a C prefix and a corresponding COMPLEX DOUBLE with a CD prefix there is also a quad precision COMPLEX function with a CQ prefix Examples are SIN CSIN CDSIN CQSIN Chapter4 Statements 115
121. Expressions 3 Example Exponentiation to a floating point power is not allowed demo cat ConstExpr f parameter 1 2 0 3 0 2 5 write t end demos 77 ConstExpr f ConstExpr f MAIN ConstExpr f line 1 Warning parameter t set to a nonconstant demo a out 31 1769 demo Record Assignment The general form of record assignment is v e e A record or record field v A record or record field Both e and v must have the same structure That is each must have the same number of fields and corresponding fields must be of the same type and size 84 FORTRAN 77 Language Reference May 2000 Example A record assignment and a record field assignment STRUCTURE PRODUCT EGER 4 ID RACTER 16 NAME RACTER 8 MODEL x4 COST 4 PRICE D STRUCTURE ECORD PRODUCT CURRENT PRIOR NEXT LINE 10 03 PPP PH wD NEXT CURRENT CURRENT 82 Q C zZ H H l5 wo In the above example the first assignment statement copies one whole record all five fields to another record the second assignment statement copies a whole record into the first element of an array of records the WRITE statement writes a whole record and the last statement sets the ID of one record to 82 Evaluation of Expressions The following restrictions apply to a
122. HR A B CHARACTER A 8 REAL B 10 10 RETURN END CALL RANK EOS WRITE OK Normal Return 0 STOP 8 WRITE Minor 1st alternate return STOP 9 WRITE Major 2nd alternate return END SUBROUTINE RANK IF EQ 0 RETURN IF EO 1 RETURN 1 RETURN 2 END Example 2 Standard alternate returns PROGRAM TESTALT In this example the RETURN 1 statement refers to the first alternate return label first The RETURN 2 statement refers to the second alternate return label second specified in the SUBROUTINE statement FORTRAN 77 Language Reference May 2000 248 209 TIPE The TYPE 5 statement writes to stdout YPE f iolist YPE grname Parameter Description f Format identifier iolist List of variables substrings arrays and records grname Name of the namelist group Description The TYPE statement is provided for compatibility and is equivalent to PRINT f iolist PRINT grname WRITE f iolist WRITE grname Example Example Formatted and namelist output INTEGER V 5 REAL X 9 Y NAMELIST GNAM X Y YPE 1 V 1 FORMAT 5 I3 YPE GNAM Chapter 4 Statements The Type Statement The type statement specifies the data type of items in
123. However these defaults can be changed by compiling with certain special options A REAL element has a sign bit an 8 bit exponent and a 23 bit fraction These REAL elements in f77 conform to the IEEE standard REAL 4 The REAL 4 data type is a synonym for REAL except that it always has a size of 4 bytes independent of any compiler options REAL 8 Double Precision Real The REAL 8 data type is a synonym for DOUBLE PRECISION except that it always has a size of 8 bytes independent of any compiler options REAL 16 Quad Real SPARC only The REAL 16 data type is a quadruple precision real The size for a REAL 16 item is 16 bytes A REAL 16 element has a sign bit a 15 bit exponent and a 112 bit fraction These REAL 16 elements in 177 conform to the IEEE standard for extended precision FORTRAN 77 Language Reference May 2000 30 Size and Alignment of Data Types Storage and alignment are always given in bytes Values that can fit into a single byte are byte aligned The size and alignment of types depends on various compiler options and platforms and how variables are declared The maximum alignment in COMMON blocks is to 4 byte boundaries Default data alignment and storage allocation can be changed by compiling with special options such as aligncommon f dalign dbl_align_all db1 xmemalign 28 12 and xtypemap The default descriptions in this manual assume that these options are n
124. J2 I4 12 2 1 DP 6 4D0 QP 1 R4 DP R16 QP C8 R1 08 3 0 5 0 I2 8 616 C8 c 1 R4 12 Character Expressions A character expression is an expression whose operands have the character type It evaluates to a single value of type character with a size of one or more characters The only character operator is the concatenation operator Expression Meaning a z Concatenate a with z The result of concatenating two strings is a third string that contains the characters of the left operand followed immediately by the characters of the right operand The value of a concatenation operation a z is a character string whose value is the value of a concatenated on the right with the value of z and whose length is the sum of the lengths of a and z The operands can be any of the following kinds of data items m Character constant m Character variable FORTRAN 77 Language Reference May 2000 76 Character array element Character function Substring Structured record field if it evaluates to a scalar character data item Examples Character expressions assuming C S and R C are characters wxy AB wxy 0 C 58 C 4 7 R C Note the following nonstandard exceptions Control characters One way to enter control characters is to hold down the Control key and press another key Most control characters can be entered
125. LSE IF ELSE or END IF statement with the same IF level as the block IF statement If the last statement of the IF block does not result in a branch to a label control is transferred to the next END IF statement that has the same IF level as the block IF statement preceding the IF block Restrictions Control cannot jump into an IF block from outside the IF block Examples Example 1 IF THEN ELSE IF L THE N N 1 CALL CALC ELSE K K 1 CALL DISP END IF Chapter4 Statements 1 Example 2 IF THEN ELSE IF with ELSE IF IF C EQ 8 THE NA NA 1 CALL APPEND SE IF C EQ THEN NB NB 1 CALL BEFOR SE IF C EQ c THEN NC NC 1 CALL CENTER END IF Example 3 Nested IF THEN ELSE IF PRESSURE GT 1000 0 THEN IF LT 0 0 THEN 0 0 Y 0 0 ELSE Z 0 0 END IF SE IF TEMPERATURE GT 547 0 THEN Z 1 0 SE 0 0 END IF 172 FORTRAN 77 Language Reference May 2000 IF Logical The logical IF statement executes one single statement or does not execute it depending on the value of a logical expression IF 6 st Parameter Description e Logical expression st Executable statement Description The l
126. MALLOC and assign the address of that block of memory to the pointer P Chapter4 Statements 213 Example 5 Dynamic allocation of arrays PROGRAM UsePointers REAL X POINTER P X READ Nsize Get the size P MALLOC Nsize Allocate the memory CALL CALC X Nsize SUBROUTINE CALC A N REAL A N Use the array of whatever size RETURN END This is a slightly more realistic example The size might well be some large number say 10 000 Once that s allocated the subroutines perform their tasks not knowing that the array was dynamically allocated 214 FORTRAN 77 Language Reference May 2000 215 Example 6 One way to use pointers to make a linked list in 77 demo cat Linked f STRUCTURE NodeType ul EGER recnum CHARACTER 3 label 1 EGER next URE odeType r b pr r pb b malloc 12 Create the base record b pb Make pr point to b 1 LE 4 Initialize create records IF NodeNum NE 1 pr r next CALL struct_creat pr NodeNum odeNum Node um 1 END DO r next Show all records NE 0 PRINT r recnum pr r next pb 1 END DO E struct_creat pr Num D STRUC RECORD POINTER odeNum DO WHILE NodeNum DO WHILE pr pb pr END SUBROUTI STRUCTURE NodeType 1 EGER recnum CHARACTER 3 label INTEGER
127. MPLICIT statements of a program unit The FORTRAN 77 Standard restricts this usage to only once For 77 if a letter is used twice each usage is declared in order See Example 4 Chapter4 Statements 175 Examples Example 1 IMPLICIT everything is integer EGER A Z IMPLICIT INT 1 STRING 0 Example 2 Complex if it starts with U V w character if it starts with C or S C S E is specified in the beginning All the EGER and A through C implies REAL INT CHARACTER 4 IMPLICIT COMPLEX U V W Ul 1 0 3 0 STRING 8000 I 0 X 0 0 Example 3 All items must be declared PLICIT NONE HARACTER STR 8 TEGER N FAL Y 100 1 0E5 STR Length 4 2 0 In the above example once IMPLICIT NONI variables must be declared explicitly Example 4 A letter used twice IMPLICIT INTEGER A Z IMPLICIT REAL A C C 1 5E8 D 9 In the above example through 2 implies FORTRAN 77 Language Reference May 2000 176 INCLUDE The INCLUDE statement inserts a file into the source program INCLUDE file Parameter Description file Name of the file to be inserted INCLUDE file Description The contents of the named file replace the INCLUDE statement Search Path If the name referred to by
128. N X the variable X is a REAL 8 element in memory interpreted as one double width real number If you do not specify the size a default size is used The default size for a declaration such as DOUBLE PRECISION X can be altered by compiling with any of the options db1 28 or xtypemap See the discussion in Chapter 2 for details REAL 8 For a declaration such as REAL 8 X the variable X is always an element of type REAL 8 in memory interpreted as a double width real number Example DOUBLE PRECISION R S 3 6 REAL 8 T 1 0 5 FORTRAN 77 Language Reference May 2000 136 E block ELS ELSE The ELSE statement indicates the beginning of an IF e THEN ELSE END IF where 6 is a logical expression Description Execution of an ELSE statement has no effect on the program END IF statement at the same IF level ELSE block ELSE block consists of all the executable statements following the ELSE statements up to but not including the next statement See IF Block on page 170 for more information ELSE block can be empty An as the ELSE An Restrictions You cannot jump into an ELSE block from outside the The statement label if any of an ELSE statement cannot be referenced by any statement END IF statement of the sam
129. NT in the FORM variable for logical units opened as print files It returns 1 for the unit number of an unopened file Special Uses of OPEN If a logical unit is already open an OPEN statement using the BLANK option does nothing but redefine that option As a nonstandard extension if a logical unit is already open an OPEN statement using the FORM option to switch between FORM PRINT and FORM FORMATTED does nothing but redefine that option These forms of the OPEN statement need not include the file name and must not include a file name if UNIT refers to standard input output or standard error Chapter5 Input and Output 267 If you connect a unit with OPEN and do not use the file name parameter then you get the default file name fort nn where nn is the unit number Therefore to redefine the standard output as a print file use OPEN UNIT 6 FORM PRINT Scratch Files Scratch files are temporary files that normally disappears after execution is completed Example Create a scratch file OPEN UNIT 7 STATUS SCRATCH To prevent a temporary file from disappearing after execution is completed you must execute a CLOSE statement with STATUS KEEP KEEP is the default status for all other files Example Close a scratch file that you want to access later CLOSE UNIT 7 STATUS KEEP Remember to get the real name of the
130. NaN NaN NaN NaN Uno Uno Uno Uno Uno E and the others EQ GT Inf NaN NaN Inf TRU Extreme Values Division Right Operand 0 Sub Num NaN 0 0 Inf Num Num Inf Num Num Inf Inf Inf NaN NaN NaN Extreme Values Comparison Right Operand 0 Sub Num lt lt gt lt gt gt gt gt gt Uno Uno Uno TABLE C 6 Left Operand 0 Sub Num Inf NaN TABLE C 7 Left Operand 0 Sub Num Inf NaN Notes If either or Y is NaN then X NE Y is GE LT LE are FALSE 0 compares equal to 0 If any argument is NaN then the results of MAX or MIN are undefined Bits and Bytes by Architecture The order in which the data the bits and bytes are arranged differs between VAX computers on the one hand and SPARC computers on the other 369 Data Representations Appendix C The bytes in a 32 bit integer when read from address n end up in the register as shown in the following tables TABLEC 8 Bits and Bytes for Intel and VAX Computers Byte n 3 Byte n 2 Byte n 1 Byte n 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00 Most Significant Least significant TABLE 0 9 Bits and Bytes for 680x0 and SPARC Computers Byte n Byte n 1 Byte n 2 Byte n 3 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 09 08 07 06 05 04 03 02 01
131. O An alternative is to use shell redirection to externally redefine the above units To redefine default blank control or the format of the standard input or output files use the OPEN statement specifying the unit number and no file name and use the options for the kind of blank control you want I O Errors Any error detected during I O processing causes the program to abort unless alternative action has been provided specifically in the program Any I O statement can include an ERR clause and IOSTAT clause to specify an alternative branch to be taken on errors and return the specific error code Read statements can include END n to branch on end of file File position and the value of I O list items are undefined following an error END catches both EOF and error conditions ERR catches only error conditions If your program does not trap I O errors then before aborting an error message is written to stderr with an error number in square brackets and the logical unit and I O state The signal that causes the abort is IOT Error numbers less than 1000 refer to operating system errors see int ro 2 Error numbers greater than or equal to 1000 come from the I O library For external I O part of the current record is displayed if the error was caused during reading from a file that can backspace For internal I O part of the string is printed with a vertical bar at the current position in the string Genera
132. OMATIC Chapter4 Statements 97 BACKSPACE The BACKSPACE statement positions the specified file to just before the preceding record BACKSPACE u BACKSPACE UNIT u IOSTAT i0s ERR s Parameter Description u Unit identifier of the external unit connected to the file ios I O status specifier integer variable or an integer array element s Error specifier s must be the label of an executable statement in the same program unit in which the BACKSPACE statement occurs Program control is transferred to the label in case of an error during the execution of the BACKSPACE statement Description BACKSPACE in a terminal file has no effect u must be connected for sequential access Execution of a BACKSPACE statement on a direct access file is not defined in the FORTRAN 77 Standard and is unpredictable recommend using a BACKSPACE statement on a direct access file or an We do not append access file BACKSPACE on a file opened as FORM BINARY is not allowed a runtime error and causes Execution of the BACKSPACE statement modifies the file position as follows Prior to Execution After Execution Beginning of the file Remains unchanged Beyond the endfile record Before the endfile record Beginning of the previous record Start of the same record FORTRAN 77 Language Reference May 2000 98 99 Statements Chapt
133. OMMON statements and 1 additional rules can apply For such rules refer to the notes on the COMMON statement C 2 3 EQUIVALENCE A C 1 B C 2 Example CHARACTER A 4 B 4 The association of A B and C can be graphically illustrated as follows The first seven character positions are arranged in memory as follows 04 05 06 07 A 4 B 1 B 2 B 3 B 4 C 2 1 C 2 2 C 2 3 03 A 3 C 1 3 01 02 A 1 A 2 C 1 1 C 1 2 FORTRAN 77 Language Reference May 2000 A 6 154 EXTERNAL The EXTERNAL statement specifies procedures or dummy procedures as external and allows their symbolic names to be used as actual arguments EXTERNAL proc proc Parameter Description proc Name of external procedure dummy procedure or block data routine Description If an external procedure or a dummy procedure is an actual argument it must be in an EXTERNAL statement in the same program unit If an intrinsic function name appears in an EXTERNAL statement that name refers to some external subroutine or function The corresponding intrinsic function is not available in the program unit Restrictions ERNAL statements H A subroutine or function name can appear in only one of the EX of a program unit A statement function name must not appear in an EXTERNAL statement Chapt
134. PRICE END STRUCTURE La 148 FORTRAN 77 Language Reference May 2000 END UNION The END UNION statement terminates the UNION statement and requires the following syntax END UNION Description See UNION and MAP on page 253 for more information Example UNION AP CHARACTER 16 END MAP AP INTEGER 2 CREDITS CHARACTER 8 GRAD_DATE END MAP END UNION Chapter 4 Statements 149 BNTRY The ENTRY statement defines an alternate entry point within a subprogram ENTRY en fal fa Parameter Description en Symbolic name of an entry point in a function or array name subroutine subprogram fa Formal argument it can be a variable name formal procedure name or an asterisk specifying an alternate return label Description Note these nuances for the ENTRY statement Procedure References by Entry Names An ENTRY name used in a subroutine subprogram is treated like a subroutine and ENTRY name used in a can be referenced with a CALL statement Similarly the 1 function subprogram is treated like a function and can be referenced as a function reference An entry name can be specified in an EXTERNAL statement and used as an actual argument It cannot be used as a dummy argument Execution of an ENTRY subprogram subroutine or function begin
135. R FORTRAN programs normally put scratch files in the current working directory If the TMPDIR environment variable is set to a writable directory then the program puts scratch files there FILEOPT fopt gt The FILEOPT fopt clause is optional fopt is a character expression Possible values are NOPAD BUFFER n and EOF NOPAD Do not extend records with blanks if you read past the end of record formatted input only That is a short record causes an abort with an error message rather than just filling with trailing blanks and continuing BUFFER n Sets the buffer size to be used by the I O unit to n bytes This suboption is intended for use with regular files such as disk files For good performance the buffer size should e a multiple of the page size Using large buffers generally improves the performance of sequential I O Performance of direct I O is usually best if the buffer size equals the record length One exception is that if the record length is one the buffer size should be at least one page Normally the BUFFER suboption should not be used with tape files where the proper buffer size is determined by the tape hardware the controllers and the file system Some kinds of tape drives offer limited functionality These limitations can cause normal Fortran I O to be unreliable The tape I O routines in the Fortran library see topen 3F are recommended alternatives for such drives
136. R 2 INTEGER 4 INTEGER 2 INTEGER 4 INTEGER 2 INTEGER 4 VMS Bit Manipulation Functions Continued Argument Type R 2 R 4 R 2 R 4 R 2 R 4 R 2 R 4 R 2 R 4 Intrinsic Functions INTEG INTEG INTEG INTEG INTEG INTEG INTEG INTEG INTEG INTEG Chapter 6 Function Bitwise exclusive OR of al a2 Bitwise complement In al set bit a2 1 In al set bit a2 to 1 return new al In al set bit a2 to 1 return new al If bit a2 of al is 1 return TRUE In al set bit a2 to 0 return new al c TABLE 6 11 Specifi Names IIEOR JIEOR LR LR INOT JNOT IIBSE JIBSE BITES BJTES IIBCI JIBCI Generic Name IEOR NOT IBSET BTEST IBCLR VMS Multiple Integer Types The possibility of multiple integer types is not addressed by the FORTRAN Standard 77 copes with their existence by treating a specific INTEGER to INTEGER function name IABS and so forth as a special sort of generic The argument type is used to select the appropriate runtime routine name which is not accessible to the programmer VMS FORTRAN takes a similar approach but makes the specific names available Result Type ER 2 ER 4 H Q ER 2 ER 4 ER 2 ER 4 ER 2
137. R p e p e In this alternate form the type of the constant expression determines the type of the name no conversion is done Description e can be of any type and the type of symbolic name and the corresponding expression must match A symbolic name can be used to represent the real part imaginary part or both parts of a complex constant A constant expression is made up of explicit constants and parameters and the FORTRAN operators See Constant Expressions on page 83 for more information No structured records or record fields are allowed in a constant expression Exponentiation to a floating point power is not allowed and a warning is issued If the type of the data expression does not match the type of the symbolic name then the type of the name must be specified by a type statement or IMPLICIT statement prior to its first appearance in a PARAMETER statement otherwise conversion will be performed If a CHARACTER statement explicitly specifies the length for a symbolic name then the constant in the PARAMETER statement can be no longer than that length Longer constants are truncated and a warning is issued The CHARACTER statement must appear before the PARAMETER statement Chapter 4 Statements 207 If a CHARACTER statement uses to specify the length for a symbolic name then the data in the PARAMETER statement are used to determine the lengt
138. RAN I O from an exception handler amounts to recursive I O See the next point Recursive I O does not work reliably If you list a function in an I O list and if that function does I O then during runtime the execution may freeze or some other unpredictable problem may occur This risk exists independent of parallelization Example Recursive I O fails intermittently PRINT x f x Not allowed because f does I O END FUNCTION F X PRINT X RETURN END FORTRAN 77 Language Reference May 2000 218 Examples Example 1 Formatted scalars CHARACTER TEXT 16 PRINT 1 NODE TEXT 1 FORMAT I2 A16 Example 2 List directed array PRINT I J VECTOR I I 1 5 Example 3 Formatted array INTEGER VECTOR 10 PRINT 12 12 I J VECTOR Example 4 Namelist CHARACTER LABEL 16 REAL QUANTITY INTEGER NODE NAMELIST SUMMARY LABEL QUANTITY NODE PRINT SUMMARY Chapter4 Statements 219 PROGRAM The PROGRAM statement identifies the program unit as a main program PROGRAM pgm Parameter Description pgm Symbolic name of the main program Description For the loader the main program is always named MAIN The PROGRAM statement serves only the person who reads the program Restrictions The PROGRAM statement can appear only as the first statement of t
139. RY HLEP A B C RETURN ENTRY MOOZ RETURN In the above example the subroutine FIN has two alternate entries the entry HLEP has an argument list the entry MOOZ has no argument list Chapter 4 Statements 151 Example 2 In the calling routine you can call the above subroutine and entries as follows INTEGER A B CHARACTER C 4 CALL FIN A B C CALL MOOZ CALL HLEP A B C In the above example the order of the call statements need not match the order of the entry statements Example 3 Multiple entry points in a function REAL FUNCTION F2 2 2 0 RETURN j ENTRY F3 X FS 3 09 KX RETURN ENTRY FHALF X FHALF X 2 0 RETURN END FORTRAN 77 Language Reference May 2000 152 EQUIVALENCE The EQUIVALENCE statement specifies that two or more variables or arrays in a program unit share the same memory EQUIVALENCE nlist nlist Parameter Description nlist List of variable names array element names array names and character substring names separated by commas Description An EQUIVALENCE statement stipulates that the storage sequence of the entities whose names appear in the list nlist must have the same first memory location An EQUIVALENCE statement can cause association of entities other than
140. Reference May 2000 64 Address and Memory No storage for the variable is allocated when a pointer based variable is defined so you must provide an address of a variable of the appropriate type and size and assign the address to a pointer usually with the normal assignment statement or data statement The loc malloc and free routines associate and deassociate memory addresses with pointers These routines are described in Chapter 6 When compiled for 64 bit environments pointers declared by the POINT statement are INTEGER 8 values Address by LOC Function You can obtain the address from the intrinsic function LOC Example Use the LOC function to get an address ptrl f Assign an address via LOC POINTER P V CHARACTER A 12 V 12 DATA A ABCDEFGHIJKL P LOC A PRINT V 5 5 END In the above example the CHARACTER statement allocates 12 bytes of storage for A but no storage for V It merely specifies the type of V because V is a pointer based variable then assign the address of A to P so now any use of V will refer to A by the pointer P The program prints an E When compiled for 64 bit environments LOC returns an INTEGER 8 value The receiving variable must be either a pointer or an INTEGER 8 variable to avoid possible address truncation Memory and Address by MALLOC Function The function MALLOC all
141. Standard the END statement cannot be continued but 77 allows this practice No other statement such as an END IF statement can have an initial line that appears to be an END statement Example Example END RAM MAIN Very little 142 FORTRAN 77 Language Reference May 2000 END DO The END DO statement terminates a DO loop and requires the following syntax END DO Description The END DO statement is the delimiting statement of a Block DO statement If the statement label is not specified in a DO statement the corresponding terminating statement must be an END DO statement You can branch to an END DO statement only from within the range of the DO loop that it terminates Examples Example 1 A DO loop with a statement number 10 END DO Example 2 A DO loop without statement number DO 1 100 END DO Chapter4 Statements 3 BND FILE The END FILE statement writes an end of file record as the next record of the file connected to the specified unit END FILE Uu END FILE UNIT IOSTAT i0s ERR s Parameter Description 1 Unit identifier of an external unit connected to the file The options can be specified in any order but if UNIT is omitted then u must be first iost I O status specifier an integer variable or an integer array element 5 Error specifier s mu
142. Sun Performance WorkShop Personal Edition except that the Fortran compilers in that product no longer support the creation of automatically parallelized or explicit directive based parallel code This capability is still supported in the Fortran compilers in Forte for High Performance Computing We appreciate your continued use of our development products and hope that we can continue to fulfill your needs into the future Contents Preface 1 Elements of FORTRAN 11 Standards Conformance 11 Extensions 12 Basic Terms 12 Character Set 12 Symbolic Names 14 Program Units 16 Statements 16 Source Line Formats 17 Data Types and Data Items 3 Types 23 CHARACTER 26 COMP LEX 26 DOUBLE PRECISION 27 INTEGER 28 LOGICAL 29 REAL 30 Constants 3 Variables 47 Arrays 48 Substrings 54 Structures 56 Pointers 63 Expressions 69 Expressions Operators and Operands 9 Arithmetic Expressions 70 Character Expressions 76 Logical Expressions 80 Relational Operator 82 Constant Expressions 83 Record Assignment 84 Evaluation of Expressions 85 Statements 87 ACCEPT 88 ASSIGN 89 Assignment 91 AUTOMATIC 96 BACKSPACE 98 BLOCK DATA 0 BYTE 102 CALL 103 CHARACTER 107 CLOSE 110 COMMON 112 FORTRAN 77 Language Reference May 2000 vi Contents COMPLEX 114 COMPLEX 115 CONTINUE 117 DATA 118 DECODE ENCODE 121 DIMENSION 3
143. T Some kind of minor catastrophe Q CALL OOPS TEXT STOP D UBROUTINE OOPS 5 HARACTER S 32 RITE 8 ETURN D 1 0 Example 2 Alternate return CALL RANK Fe o st WRITE OK Normal Return STOP 8 WRITE Minor 1st alternate return STOP 9 WRITE Major 2nd alternate return END SUBROUTINE RANK N IF EQ 0 RETURN IF EQ 1 RETURN 1 RETURN 2 END 234 FORTRAN 77 Language Reference May 2000 REWIND The REWIND statement positions the file associated with the specified unit to its initial point Note Use the TOPEN routines to rewind tape devices See the Fortran Library EWIND ina Reference for details REWIND u REWIND UNIT IOSTAT ios ERR 8 Parameter Description u Unit identifier of an external unit connected to the file u must be connected for sequential access or append access ios I O specifier an integer variable or an integer array element s Error specifier s must be the label of an executable statement in the same program in which this REWIND statement occurs The program control is transferred to this label in case of an error during the execution of the REWIND statement Description The options can be specified in any order Rewinding a unit not assoc
144. TEGER 8 when compiling for 64 bit environments The value returned by LOC or MALLOC should be stored in variables typed POINTER EGER 4 or INTEGER 8 in 64 bit environments The argument to FREE must be INT the value returned by a previous call to MALLOC and hence should have data type POINTER INTEGER 4 or INTEGER 8 MALLOC64 always takes an INTEGER 8 argument size of memory request in bytes and always returns an INTEGER 8 value Use this routine rather than MALLOC when compiling programs that must run in both 32 bit and 64 bit environments The receiving variable must be declared either POINTER or INTEGER 8 18 The SIZEOF intrinsic cannot be applied to arrays of an assumed size characters of a length that is passed or subroutine calls or names SIZEOF returns default EGER 4 data If compiling for a 64 bit environment the compiler will issue a INT warning if the result overflows the INTEGER 4 data range To use SIZEOF in a 64 bit environment with arrays larger than the INTEGER 4 limit 2 Gbytes the SIZEOF function and the variables receiving the result must be declared INTEGER 8 VMS Intrinsic Functions section lists VMS FORTRAN intrinsic routines recognized by 77 They are of This course nonstandard FORTRAN 77 Language Reference May 2000 344
145. TRUE or FALSE depending on the value of the variable ARG Example 2 Real function FUNCTION SOR A SOR A A RETURN END In the above example the function SQR is defined as function of type REAL by default and returns the square of the number passed to it Example 3 Size of function alternate syntax INTEGER FUNCTION FCN 2 A B C The above nonstandard form is treated as INTEGER 2 FUNCTION FCN A B C Chapter4 Statements 163 GO TO Assigned The assigned GO TO statement branches to a statement label identified by the assigned label value of a variable GO TO i s s Parameter Description i Integer variable name 5 Statement label of an executable statement Description Execution proceeds as follows At the time an assigned GO TO statement is executed the variable i must have been assigned the label value of an executable statement in the same program unit as the assigned GO TO statement If an assigned GO TO statement is executed control transfers to a statement identified by i If a list of statement labels is present the statement label assigned to i must be one of the labels in the list Restrictions i must be assigned by an ASSIGN statement in the same program unit as the GO TO statement i must be INTEGER 4 or INTEGER 8 not INTEGER 2 s must be in the
146. Type Sequential Direct Formatted Internal The file is a character variable The file is a character substring array or array array each record is one element array element External Only formatted records of same Only formatted records or variable length all the same length Chapter5 Input and Output 5 TABLE 5 1 Summary of 77 Input and Output Continued Kind of I O Access Mode Form File Type Sequential Direct Unformatted Internal Not allowed Not allowed External Contains only unformatted READ Gets one logical records record at a time WRITE Unfilled part of record is undefined Binary Internal Not allowed Not allowed External Contains only unformatted raw Not allowed binary data no record marks List directed Internal READ Reads characters until Not allowed EOF or I O list is satisfied WRITE Writes records until list is satisfied External Uses standard formats based on Not allowed type of variable and size of element Blanks or commas are separators Any columns NAMELIST Internal Not allowed Not allowed External READ Reads records until it Not allowed finds groupname in columns 2 80 Then reads records searching for names in that group and stores data in those variables Stops reading on or eof WRITE Writes records showing the group name and each variable name with value Avoid list directed internal writes The number of lines and items per line varies wi
147. YTE CHARACTER CHARACTER n where n must be greater than zero CHARACTER COMP LEX COMPLEX 8 COMPLEX 16 COMPLEX 32 amp DOUBLE COMPLEX DOUBLE PRECISION INTEGER INTEGER 2 INTEGER 4 INTEGER 8 LOGICAL LOGICAL 1 LOGICAL 2 LOGICAL 4 LOGICAL 8 REAL REAL 4 amp REAL 8 REAL 16 4 OR OH OW fun Symbolic name assigned to function ar Formal argument name COMPLEX 32 and REAL 16 are SPARC only An alternate nonstandard syntax for length specifier is as follows type FUNCTION fun m ar ar Parameter Description m Unsigned nonzero integer constant specifying length of the data type ar Formal argument name Chapter4 Statements 161 Description Note the type value and formal arguments for a FUNCTION statement Type of Function The function statement involves type name and formal arguments If type is not present in the FUNCTION statement then the type of the function is determined by default and by any subsequent IMPLICIT or type statement If type is present then the function name cannot appear in other type statements Note Compiling with any of the options db1 28 12 or xt ypemap can alter the default data size assumed in the call to or definition of functions unless the data type size is explicitly declared See Chapter 2 and the Fortran User Guide for details on these options Value of Function The
148. a machine with the same architecture Chapter5 Input and Output 307 Sequential Access I O Logical record length for unformatted sequential files is determined by the number of bytes required by the items in the I O list The requirements of this form of I O cause the external physical record size to be somewhat larger than the logical record size Example WRITE 8 A B The FORTRAN runtime system embeds the record boundaries in the data by inserting an INTEGER 4 byte count at the beginning and end of each unformatted sequential record during an unformatted sequential WRITE The trailing byte count enables BACKSPACE to operate on records The result is that FORTRAN programs can use an unformatted sequential READ only on data that was written by an unformatted sequential WRITE operation Any attempt to read such a record as formatted would have unpredictable results Here are some guidelines Avoid using the unformatted sequential READ unless your file was written that way Because of the extra data at the beginning and end of each unformatted sequential record you might want to try using the unformatted direct I O whenever that extra data is significant It is more significant with short records than with very long ones Direct Access I O If your I O lists are different lengths you can OPEN the file with the RECL 1 option This signals FORTRAN to use the I O list to determine how many items
149. above example the first input data item has no decimal point so D8 3 determines the decimal point The other input data items have decimal points so those decimal points override the D edit descriptor as far as decimal points are concerned Example Real output with D editing in the program Dout f R 1234 678 PRINT 1 R R R 1 FORMAT D9 3 D8 4 D13 4 END The above program displays 0 123D 04 AAAO 1235D 04 In the above example the second printed line is asterisks because the D8 4 does not allow for the sign in the third printed line the D13 4 results in three leading blanks Chapter5 Input and Output 295 E Editing The E specifier is for the exponential form of decimal real data items The general form is E w d Ee w indicates that the field to be edited occupies w positions d indicates that the fractional part of the number the part to the right of the decimal point has d digits However if the input datum contains a decimal point that decimal point overrides the d value e indicates the number of digits in the exponent field The default is 2 The specified input output list item must be of type real On input the specified list item becomes defined with a real datum On output the specified list item must be defined as a real datum The output field for the Ew d edit specifier has the widt
150. ads 980 0 into the first 5 elements of the array PST The form r skips r elements of an array that is does not change them where r is an unsigned integer constant Example NAMELIST input with some skipped data 3 5 980 The other input is ASGRID PSI The program nam3 f with the above input skips the first 3 elements and loads 980 0 into elements 4 5 6 7 8 of PSI Name Requests If your program is doing NAMELIST input from the terminal you can request the group name and NAMELIST names that it accepts To do so enter a question mark in column two and press Return The group then displayed The program then waits again for name and variable names are input FORTRAN 77 Language Reference May 2000 322 323 Example Requesting names demo cat nam4 f nam4 f Namelist requesting names CHARACTER 14 SAMPLE OGICAL 4 NEW REAL 4 DELTA NAMELIST CASE SAMPLE NEW DELTA WRITE Input READ CASE END demo 77 silent nam4 f demo a out Input A lt Keyboard Input AScase Asample Anew Adelta ASend 480886 sample Test 2 delta 0 03 lt Keyboard Input demo Chapter 5 Input and Output 324 FORTRAN 77 Language Reference May 2000 Intrinsic Functions This chapter tabulates and explains the set of intrinsic functions that are
151. ained within either a structure declaration or a union declaration You can use a previously defined record within a structure declaration Example Define structure SALE using previously defined record PRODUCT STRUCTURE SALE HARACTER 32 BUYER TEGER 2 QUANTITY ECORD PRODUCT ITEM END STRUCTURE FORTRAN 77 Language Reference May 2000 60 In the above example the structure SALE contains three fields BUYER QUANTITY and ITEM where ITEM is a record with the structure PRODUCT Structure Within a Structure You can nest a declaration within a declaration Example If PRODUCT is not declared previously then you can declare it within the declaration of SALE STRUCTURE SALE CHARACTER 32 BUYER INTEGER 2 QUANTITY STRUCTURE PRODUCT ITEM INTEGER 4 ID CHARACTER 16 NAME CHARACTER 8 ODEL R R EAL 4 COST EAL 4 PRICE END STRUCTURE END STRUCTURE Here the structure SALE still contains the same three fields as in the prior example BUYER QUANTITY and ITEM The field ITEM is an example of a field list in this case a single element list as defined under Structure Declaration The size and complexity of the various structures determine which style of substructure declaration is best to use in a given situation Field Reference in Subs
152. al and they are then used as the real part of a complex operand with the imaginary part set to zero Chapter 3 Expressions 3 Numeric operations are allowed logical variables You can use a logical value any place where the FORTRAN Standard requires a numeric value The numeric can be integer real complex double precision double complex or real 16 SPARC only The compiler implicitly converts the logical to the appropriate numeric If you use these features your program may not be portable Example Some combinations of both integer and logical types COMPLEX Cl 1 0 2 0 INTEGER 2 11 12 3 061020 21 22 L3 L4 5 REAL R1 1 0 DATA 11 8 12 W 13 0 DATA L1 TRUE L2 TRUE L3 TRUE L4 TRUE amp 5 TRUE 1 gt 1 1 12 NOT 2 L2 11 AND 3 L3 11 OR 2 Cl Ee 1 a ll aw Resultant Type For integer operands with a logical operator the operation is done bit by bit The result is an integer If the operands are mixed integer and logical then the logicals are converted to integers and the result is an integer Arithmetic Assignment The arithmetic assignment statement assigns a value to a variable array element or record field The syntax is v e e Arithmetic expression a character constant or a logical expression v Numeric variable array element or recor
153. al statement must not be one of the following statements Unconditional GO TO Assigned GO TO Arithmetic IF Block IF ELSE IF ELSE DIF ETURN T 5 D DO DO WHILI If the terminal statement is a logical IF statement it can contain any executable statement except Chapter4 Statements 1 1 2 DO DO WHILE Block IF ELSE IE ELSE END IE END Logical IF If s is not specified the DO WHILE loop must end with an END DO statement DO WHILE Loop Range The range of a DO WHILE loop consists of all the executable statements that appear following the DO WHILE statement up to and including the terminal statement If a DO WHILE statement appears within the range of another DO WHILE loop its range must be entirely contained within the range of the outer DO WHILE loop More than one DO WHILE loop can have the same terminal statement If a DO WHILE statement appears within an IF ELSE IF or ELSE block the range of the associated DO WHILE loop must be entirely within that block If a block IF statement appears within the range of a DO WHILE loop the corresponding END IF statement must also appear within the range of that DO WHILE loop Terminal Statement Processing After the terminal statement of a DO WHILE loop is executed control is transferred back to the corresponding DO WHILE statem
154. alues by a DATA EAD statement and so forth element of an array a substring a field 0 of any of the above and so forth Integer array The integer array can g statement an assignment statement a RI You must provide the delimiting left and right parentheses but not the word g enough to hold the entire format For NTEGER 4 or a CHARACTER 4 object Chapter5 Input and Output 305 FORMAT and not a statement number You must declare the object so that it is bi instance 8 121 does not fit in an I Examples Runtime formats in character expressions and integer arrays demo cat runtim f CHARACTER CS 8 CHARACTER CA UE7 i ZT Tp ME tp ply 2 ef CHARACTER 5 1 7 6 INTEGER 4 IA 2 STRUCTURE STR CHARACTER 4 A 1 EGER 4 K END STRUCTURE CHARACTER 8 LEFT RIGHT RECORD STR R 9 cS 18 WRITE CS N Character Scalar CA 2 6 WRITE CA N Character Array 5 2 18 WRITE S 2 N Element of Character Array IA 1 18 WRITE IA N Integer Array R A 18 WRITE R A Field Of Record F I RIGHT 8 WRITE LEFT RIGHT N END demo 77 silent runtim f demo a out 9 9 9 9 9 9 demo Variable Format Expressions lt e gt In general inside a FORMAT statement any integer constant can be replaced by an arbitrary express
155. aration Declaration of a typed data field Record A map declaration defines alternate groups of fields in a union During execution one map at a time is associated with a shared storage location When you reference a field in a map the fields in any previous map become undefined and are succeeded by the fields in the map of the newly referenced field The amount of memory used by a union is that of its biggest map E CLASS and T from the above AJOR EDITS GRAD_DATE ERSON to have the structure STUDEN EDITS and GRAD_DATE STRUCTURE STUDENT CHARACTER 32 NAME INTEGER 2 CLASS UNION AP CHARACTER 16 END MAP AP INTEGER 2 CR CHARACTER 8 END MAP END UNION END STRUCTURE ERSON MAJOR references a field from the first map and PERSON CREDITS references a field from the second map If the variables of the second map field are initialized and then the program references the variable PERSON MAJOR the first map becomes active and the variables of the second map Example Declare the structure STUDENT to contain either NAMI MAJOR or NAME CLASS CRI If you define the variable P example then P become undefined Pointers The POINTER statement establishes pairs of variables and pointers Each pointer contains the address of its paired variable sand Data Items 63 Chapter 2 Data Type
156. as 7 dimensions REAL TAO 2 2 3 4 5 6 10 Example Lower bounds other than one REAL A 3 5 7 3 5 B 0 2 Example Character arrays CHARACTER M 3 4 7 9 4 The array M has 12 elements each of which consists of 7 characters Chapter 2 Data Types and Data Items 9 The array V has 9 elements each of which consists of 4 The following restrictions on bounds apply Both the upper and the lower bounds can be negative zero or positive The upper bound must be greater than or equal to the lower bound If only one bound is specified it is the upper and the lower is one In assumed size arrays the upper bound of the last dimension is an asterisk Each bound is an integer expression and each operand of the expression is a constant a dummy argument or a variable in a common block No array references or user defined functions are allowed Adjustable Arrays An adjustable array is an array that is a dummy argument or local array with one or more of its dimensions or bounds as an expression of integer variables that are either themselves dummy arguments or are in a common block You can declare adjustable arrays in the usual DIMENSION or type statements In f77 you can also declare adjustable arrays in a RECORD statement if that RECORD statement is not inside a structure declaration block Example Adjustable arrays SUBROUTINE POPUP A B COMMON DEFS M L RE
157. ase see the Sun WorkShop 6 Installation Guide or your system administrator FORTRAN 77 Language Reference May 2000 2 How This Book Is Organized The FORTRAN 77 Language Reference contains the following chapters and appendixes Chapter 1 Elements of FORTRAN introduces the basic parts of Sun WorkShop FORTRAN 77 standards conformance and elements of the language Chapter 2 Data Types and Data Items describes the data types and data structures in the language including arrays substrings structures and pointers Chapter 3 Expressions discusses FORTRAN expressions and how they are evaluated Chapter 4 Statements details the statements in the FORTRAN 77 language and the extensions recognized by the Sun WorkShop compiler Chapter 5 Input and Output describes the general concepts of FORTRAN input output and provides details on the different I O operations Chapter 6 Intrinsic Functions tabulates and explains the intrinsic functions that are part of Sun WorkShop FORTRAN 77 including VAX VMS extensions Appendix A ASCII Character Set lists the standard ASCII character set Appendix B Sample Statements shows samples of selected FORTRAN 77 statements for quick reference Appendix C Data Representations introduces the way data is represented in FORTRAN Appendix D VMS Language Extensions describes the VAX VMS language extensions provided in Su
158. ate return Alternate return Initialize B and Cx Double complex 9 Quad complex Initialize U and V FORTRAN Statement Samples Continued Examples BYTE A B C BYTE A B C 10 BYTE A x B 255 C 10 CALL P A B CALL P A B 9 CALL P A B amp 9 CALL P HARACTER C 80 D 1 4 HARACTER 18 A B C HARACTER A B 3 xyz C z OY CLOSE UNIT I CLOSE UNIT U ERR 90 IOSTAT I COMMON DELTAS H P T COMMON Y Z COMMON P D Q 10 100 Uy C3769 U 16 U 32 SPARC only U 1 0 1 0 V 1 0 10 0 x x COMP LI COMPL COMPL x Aw x TABLE B 1 COMPL Name BYTE CALL CHARACTER CLOSE COMMON COMPLEX CONTINUE 100 CONTINUE DATA DATA A 60 4 01 2 b9 DATA V I I 1 3 7 8 DATA ARRAY 4 4 1 0 DATA B O X Y 2 0011111 O 37 1 Z 1 DECODE amp DECODE 4 1 S V DIMENSION DIMENSION ARRAY 4 4 DIMENSION V 1000 W 3 DO DO 100 I INIT LAST INCR 100 CONTINUE DO I INIT LAST Unlabeled DO END DO DO WHILE DIFF LE DELTA DO WHILE END DO DO 100 WHILE DIFF LE DELTA 100 CONTINUE 356 FORTRAN 77 Language Reference May 2000 357 FORTRAN Statement Samples Continued Comments COMPLEX 16 amp COMPLEX Initialize U and V REAL 8 Initialize D
159. ats on page 305 for details on formats evaluated at runtime If the optional characters FMT are omitted from the format specifier then f must appear as the second argument for a formatted write otherwise it must not appear at all f must not be an asterisk for direct access f can be an asterisk for internal files If a file is connected for formatted I O unformatted data transfer is prohibited and vice versa I O Status Specifier ios must be an integer variable integer array element or integer record field Record Number rn must be a positive integer expression This argument can appear only for direct access files rn can be specified for internal files Error Specifier s must be the label of an executable statement in the same program unit in which this WRITE statement occurs FORTRAN 77 Language Reference May 2000 258 Output List iolist can be empty or it can contain output items or implied DO lists The output items must be one of the following Variables Substrings Arrays Array elements Record fields Any other expression A simple unsubscripted array name specifies all of the elements of the array in memory storage order with the leftmost subscript increasing more rapidly Implied DO lists are described in Implied DO Lists on page 119 If the output item is a character expression that employs the concatenation operator the length specifiers of its operands can be an aste
160. ay array declarator function or dummy function len Length in characters of the symbolic constant variable array element or function 6 List of constants for the immediately preceding name Description Each character occupies 8 bits of storage aligned on a character boundary Character arrays and common blocks containing character variables are packed in an array of character variables The first character of one element follows the last character of the preceding element without holes The length len must be greater than 0 If len is omitted it is assumed equal to 1 For local and common character variables symbolic constants dummy arguments or function names len can be an integer constant or a parenthesized integer constant expression For dummy arguments or function names len can have another form a parenthesized asterisk that is CHARACTER which denotes that the function name length is defined in referencing the program unit and the dummy argument has the length of the actual argument For symbolic constants len can also be a parenthesized asterisk which indicates that the name is defined as having the length of the constant This is shown in Example 5 in the next section The list c of constants can be used only for a variable array or array declarator There can be only one constant for the immediately preceding variable and one constant for each element of the immediately preceding array Chapter
161. c name can appear only once in type statements in a program unit A type statement must precede all executable statements Example Example The type statement TEGER 2 I J 0 EAL 4 PI 3 141592654 ARRAY 10 5 0 0 5 1 0 HARACTER 10 NAME HARACTER 10 TITLE Heading In the above example J is initialized to 0 PI is initialized to 3 141592654 The first five elements of ARRAY are initialized to 0 0 The second five elements of ARRAY are initialized to 1 0 TITLE is initialized to Heading 252 FORTRAN 77 Language Reference May 2000 UNION and MAP The UNION statement defines groups of fields that share memory at runtime The syntax of a UNION declaration is as follows UNION MAP field declaration field declaration ENDMAP AP field declaration field declaration END MAP END UNION Description A MAP statement defines alternate groups of fields in a union During execution one map at a time is associated with a shared storage location When you reference a field in a map the fields in any previous map become undefined and are succeeded by the fields in the map of the newly referenced field Also m A UNION declaration can appear only within a STRUCTURE declaration The amount of memory used by a union is that of its biggest map Within a UNION declaration the order of the MAP statements is not relevant The UNION line is par
162. can it appear in an EXTERNAL statement The type of the argument is determined as if the statement function were a whole program unit in itself Even if the name of a statement function argument is the same as that of another local variable the reference is considered a dummy argument of the statement function not the local variable of the same name The length specification of a character statement function or its dummy argument of type CHARACTER must be an integer constant expression A statement function cannot be invoked recursively FORTRAN 77 Language Reference May 2000 240 Examples Example 1 Arithmetic statement function PARAMETER PI 3 14159 REAL RADIUS VOLUME SPHERE R 4 0 PI R 3 3 0 READ RADIUS VOLUME SPHERE RADIUS Example 2 Logical statement function LOGICAL OKFILE INTEGER STATUS OKFILE I LT 1 READ IOSTAT STATUS X Y IF OK FILE STATUS CALL CALC Y A Example 3 Character statement function CHARACTER FIRST 1 STR 16 S 1 FIRST S S 1 1 READ STR IF FIRST STR LT CALL CONTROL S A Chapter4 Statements 241 STATIC The STATIC statement ensures that the specified items are stored in static memory STATIC list Parameter Description list List of variables and arrays Description All loca
163. ceed the magnitude of A and whose sign is the same as the sign of A Such a mathematical integer value may be too large to fit in the computer integer type If A is type complex or double complex then apply the above rule to the real part of A If A is type real then IFIX A is the same as INT A 2 REAL If A is type real then REAL A is A If A is type integer or double precision then REAL A is as much precision of the significant part of A as a real datum can contain If A is type complex then REAL A is the real part of A If A is type double complex then REAL A is as much precision of the significant part of the real part of A as a real datum can contain 3 DBLE If A is type double precision then DBLE A is A If A is type integer or real then DBLE A is as much precision of the significant part of A as a double precision datum can contain If Ais type complex then DBLE A is as much precision of the significant part of the real part of A as a double precision datum can contain If A is type COMPLEX 16 then DBLE A is the real part of A 3 OREAL If Ais type REAL 16 then QREAL A is A FORTRAN 77 Language Reference May 2000 340 If A is type integer real or double precision then QREAL A is as much precision of the significant part of A as a REAL 16 datum can contain If A is type complex or double complex then QREAL A is as
164. cessing After the terminal statement of a DO loop is executed the following steps are performed The value of the DO variable if any is incremented by the value of e3 that was computed when the DO statement was executed The iteration count is decreased by one The iteration count is tested and if it is greater than zero the statements in the range of the DO loop are executed again Restrictions The DO variable must not be modified in any way within the range of the DO loop Control must not jump into the range of a DO loop from outside its range Comments In some cases the DO variable can overflow as a result of an increment that is performed prior to testing it against the final value When this happens your program has an error and neither the compiler nor the runtime system detects it In this situation though the Do variable wraps around the loop can terminate properly If there is a jump into the range of a DO loop from outside its range a warning is issued but execution continues anyway FORTRAN 77 Language Reference May 2000 128 When the jump is from outside to the terminal statement that is CONTINUE and this statement is the terminal statement of several nested DO loops then the most inner DO loop is always executed Examples Example 1 Nested Do loops N 0 DO 210 I 1 10 J 1 DO 200 K 5 1 L K 1 200 CONTINUE 210 CONTINUE WRITE I 1 0 0
165. claration or a record that has been previously defined Union declaration see UNION and MAP on page 253 for more information Example Example MAP STRUCTURE STUDENT CHARACTER 32 AME INTEGER 2 CLASS UNION AP CHARACTER 16 MAJOR END MAP AP INTEGER 2 CREDITS CHARACTER 8 GRAD_DATE END MAP END UNION END STRUCTURE FORTRAN 77 Language Reference May 2000 194 NAMELIST The NAMELIST statement defines a list of variables or array names and associates it with a unique group name NAMELIST grname namelist grname namelist Parameter Description grname Symbolic name of the group namelist List of variables and arrays Description The NAMELIST statement contains a group name and other items Group Name The group name is used in the namelist directed I O statement to identify the list of variables or arrays that are to be read or written This name is used by namelist directed I O statements instead of an input output list The group name must be unique and identifies a list whose items can be read or written A group of variables can be defined through several NAMELIST statements with the same group name Together these definitions are taken as defining one NAMELIST group Namelist Items The namelist items can be of any data type The items in the namelist can be variables or array
166. cords with the same number of fields such that corresponding fields are the same elementary data type Both e and v are records with the same number of fields such that corresponding fields are substructures with the same structure as defined in 2 above The sections on the RECORD and STRUCTURE statements have more details on the structure of records Chapter4 Statements 93 Examples Example 1 Arithmetic assignment INTEGER 12 2 J2 2 I4 4 REAL R1 QP 16 REAL 16 is SPARC only DOUBLE PRECISION DP COMPLEX C8 C16 16 QC 32 COMPLEX 32 is SPARC only J2 29002 I2 J2 14 12 2 1 DP 9 QP 6 409 R1 DP C8 RI C8 3 0 5 0 I2 8 C16 C8 C32 C8 Example 2 Logical assignment LOGICAL B1 1 B2 1 LOGICAL L3 L4 L4 TRUE Bl 4 82 1 Example 3 Hollerith assignment HARACTER S 4 TEGER 12 2 14 4 EAL R 4Hwxyz 2 2Hyz 4 4Hwxyz 4Hwxyz DHHNDWDHA 94 FORTRAN 77 Language Reference May 2000 95 Statements Example 4 Character assignment CHARACTER BELL 1 C2 2 C3 3 C5 5 C6 6 REAL Z 02 2 03 uvwxyz 05 vwxyz 05 1 2 JAB 66 05 C2 BELL CHAR 7 Control Character G The results of the above are C2 receives zA a trailing blank 3 receives uvw 5 receives ABxyz 6 receives ABxyzz an extra z left o
167. d NAMELIST I O NAMELIST I O produces format free input or output of whole groups of variables or input of selected items in a group of variables The NAMELIST statement defines a group of variables or arrays It specifies a group name and lists the variables and arrays of that group Chapter5 Input and Output 315 Syntax Rules The syntax of the NAMELIST statement is NAMELIST group name namelist group name namelist Parameter Description group name Name of group namelist List of variables or arrays separated by commas See NAMELIST on page 195 for details Example NAMELIST statement CHARACTER 18 SAMPLE LOGICAL 4 NEW REAL 4 DELTA NAMELIST CASE SAMPLE NEW DELTA A variable or array can be listed in more than one NAMELIST group The input data can include array elements and strings It can include substrings in the sense that the input constant data string can be shorter than the declared size of the variable Restrictions group name can appear in only the NAMELIST READ or WRITE statements and must be unique for the program list cannot include constants array elements dummy assumed size arrays structures substrings records record fields pointers or pointer based variables Example A variable in two NAMELIST groups EAL ARRAY 4 4 HARACTER 18 SAMPLE OGICAL 4 NEW EAL 4 DELTA NAMELIST CAS
168. d demo gt 77 o binf bin f end of file logical unit 1 lately reading sequential unformatted external IO named fort 1 demo gt cat bin f MAIN bin bamn demo gt binf alpha betag ammae psilo n tios FT Abort An INQUIRE on a binary file returns BINARY for the FORM parameter SEQUENTIAL for ACCESS YES for UNFORMATTED YES for SEQUENTIAL BACKSPACE on a binary file is not allowed and causes a runtime error message Input and Output Chapter 5 List Directed I O List directed I O is a free form I O for sequential access devices To get it use an asterisk as the format identifier as in READ 6 A B C Note these rules for list directed input On input values are separated by strings of blanks and possibly a comma m Values except for character strings cannot contain blanks a Character strings can be quoted strings using pairs of quotes pairs of apostrophes or unquoted strings see Unquoted Strings on page 314 but not hollerith nHxyz strings End of record counts as a blank except in character strings where it is ignored Complex constants are given as two real constants separated by a comma and enclosed in parentheses A null input field such as between two consecutive commas means that the corresponding variable in the I O list is not changed
169. d field FORTRAN 77 Language Reference May 2000 74 Assigning 10216915 to numerics is allowed but nonstandard and may not be portable The resultant data type is of course the data type of v Execution of an arithmetic assignment statement causes the evaluation of the expression e and conversion to the type of v if types differ and assignment of v with the resulting value typed according to the table below Character constants can be assigned to variables of type integer or real Such a constant can be a Hollerith constant or a string in apostrophes or quotes The characters are transferred to the variables without any conversion of data This practice is nonstandard and may not be portable Type of v Conversion of e INTEGER 2 INTEGER 4 or INTEGER 8 INT e REAL REAL e REAL 8 DBLE 6 REAL 16 SPARC only QREAL e SPARC only DOUBLE PRECISION DBLE 6 COMP LEX 8 CMP LX 6 COMP LEX 16 DCMPLX 6 COMP LEX 32 SPARC only QCMPLX e SPARC only Note Compiling with any of the options i2 db1 r8 or xt ypemap will have an effect on the assumed type of e This is discussed in Chapter 2 See also the Fortran User s Guide for a description of these options Chapter 3 Expressions 5 Example Arithmetic assignment INTEGER 12 2 J2 2 4 LOGICAL 1 2 REAL R4 4 R16 16 DOUBLE PRECISION DP COMPLEX C8 C16 16 J2 29002 I2
170. d in memory as follows A 1 1 A 2 1 A 3 1 A 1 2 A 2 2 A 3 2 The inner leftmost subscript changes more rapidly Chapter 2 Data Types and Data Items 3 Substrings A character datum is a sequence of one or more characters A character substring is a contiguous portion of a character variable or of a character array element or of a character field of a structured record A substring name can be in either of the following two forms tiet o Eez E 0 sih 8 Jie gt e1 e2 where v Character variable name als sS Character array element name el Leftmost character position of the substring e2 Rightmost character position of the substring Both e1 and e2 are integer expressions They cannot exceed the range of INTEGER 4 on 32 bit environments If the expression is not in the range 2147483648 2147483647 then the results are unpredictable When compiled for 64 bit environments the substring character position expressions can be in the range of INTEGER 8 Example The string with initial character from the Ith character of S and with the last character from the Lth character of S In the above example there are L I 1 characters in the substring The following string has an initial character from the Mth character of the array element A J K with the last character from the Nth character of that element A J K M N In the above exa
171. dard The default size for a declaration such as REAL H can be altered by compiling with any of the options db1 58 or xt ypemap See the discussion in Chapter 2 for details REAL 4 For a declaration such as REAL 4 w the variable W is always a REAL 4 element in memory interpreted as a single width real number REAL 8 For a declaration such as REAL 8 w the variable W is always a REAL 8 element in memory interpreted as a double width real number REAL 16 SPARC only For a declaration such as REAL 16 w the variable W is always an element of type REAL 16 in memory interpreted as a quadruple width real Examples Example 1 Simple real variables these declarations are all equivalent Example 2 Initialize variables REAL 16 is SPARC only EAL U 1 0 V 4 3 D 8 1 0 Q 16 4 5 FORTRAN 77 Language Reference May 2000 228 Example 3 Specify dimensions for some real arrays A 10 100 V 10 10 4 4 10 Example 4 Initialize some arrays EAL A 10 100 1000 0 0 B 2 2 1 0 2 0 3 0 4 0 Example 5 Double and quadruple precision REAL 16 is SPARC only ECISION D In the above example D and R are both double precision Q is quadruple precision Chapter4 Statements 229 RECORD The RECORD statement defines variables to have a specified structure or
172. decimal and octal constants are accepted in VMS form Example Constants Binary B Octal 0 Hexadecimal X or Z DATA NI B 0011111 15 3 2 0 37 NALA ELEY Function length on function name rather than on the word FUNCTION The compiler accepts nonstandard length specifiers in function declarations Appendix VMS Language Extensions 373 Example Size on function name rather than the word FUNCTION INTEGER FUNCTION FCN 2 A B C E and ACCEPT statements are allowed m TYP a Alternate return The nonstandard amp syntax for alternate return actual arguments is treated as the standard FORTRAN syntax Example 100 Z Standard 100 Z Nonstandard alternate syntax and DECODE statements are accepted ENCODE a The a Direct I O with N record specifier The nonstandard record specifier N for direct access I O statements is accepted Example A nonstandard form for record specifier READ LIST The above is treated as EAD UNIT K REC N LIST The logical unit number is K and the number of the record is N RECORDSIZE and TYPE options OPEN has the following alternative m NAME options NAME is treated as FILE RECORDSIZE is treated as RECL a TYPE is treated as STATUS E p clause in the CLOSE statement is treated as STATUS p POSE
173. descriptor 303 space 13 9 spaces leading hex and octal output 289 special characters 13 36 SS edit descriptor 303 standard fixed format source 17 units 263 standards conformance 11 start of heading and text 77 statement 12 16 function 239 label 12 list of all statements 17 samples 355 STATIC 242 STATUS OPEN specifier 201 stderr 263 stdin 263 stdout 263 392 FORTRAN 77 Language Reference May 2000 underscore in function or subprogram names 14 names with 14 unformatted I O 307 record size 375 376 UNION 253 union declaration 62 253 unit logical unit preattached 269 UNIT OPEN specifier 198 unsigned constant 34 upper case 14 15 V valid characters for data 14 characters in character set 14 characters in names 14 values extreme for arithmetic operations 367 variable boundary 31 definition of 47 Example FORMAT expression 160 name 14 part of iolist 217 variable formats 159 222 258 275 284 305 306 307 variable length records 200 vertical format control 266 279 space 0 1 279 vertical tab character 36 VIRTUAL 255 372 VMS FORTRAN align structures 376 features with x1 backslash 14 36 313 D or d debug lines 19 debugging lines 377 logical file names 178 375 376 parameter form 207 209 377 quotes 93 record length 200 376 features with x1 record length 184 Index 3 input data 319 322 output 317 s
174. dure name an asterisk or an ampersand Description A subroutine subprogram must have a SUBROUTINE statement as the first statement A subroutine can have any other statements except a BLOCK DATA FUNCTION PROGRAM or another SUBROUTINE statement sub is the name of a subroutine and is a global name and must not be the same as any other global name such as a common block name or a function name Nor can it be the same as any local name in the same subroutine d is the dummy argument and multiple dummy arguments are separated by commas d can be one of the following Variable name Array name Dummy procedure name Record name Asterisk or an ampersand amp The dummy arguments are local to the subroutine and must not appear in any of the following statements except as a common block name EQUIVALENCE PARAMETER SAVE STATIC AUTOMATIC INTRINSIC DATA COMMON Chapter4 Statements 247 The actual arguments in the CALL statement that references a subroutine must agree with the corresponding formal arguments in the SUBROUTINE statement in order number and type An asterisk or an ampersand in the formal argument list denotes an alternate return label A RETURN statement in this procedure can specify the ordinal number of the alternate return to be taken Examples Example 1 A variable and array as parameters 1 2 SUBROUTINE S
175. e FORTRAN 77 Standard TABLE6 7 Environmental Inquiry Functions Generic Name Argument Type Function Type EPBASE INTEGER INTEGER REAL INTEGER DOUBLE INTEGER REAL 16 INTEGER EPPREC INTEGER INTEGER REAL INTEGER DOUBLE INTEGER REAL 16 INTEGER EPEMIN REAL INTEGER DOUBLE INTEGER REAL 16 INTEGER EPEMAX REAL INTEGER DOUBLE INTEGER REAL 16 INTEGER EPTINY REAL REAL DOUBLE DOUBLE REAL 16 REAL 16 EPHUGE INTEGER INTEGER REAL REAL DOUBLE DOUBLE REAL 16 REAL 16 EPMRSP REAL REAL DOUBLE DOUBLE REAL 16 REAL 16 Chapter 6 Intrinsic Functions No of Args 1 Definition Base of Number System Number of Significant Bits Minimum Exponent Maximum Exponent Least Nonzero Number Largest Number Representable Epsilon See Note 16 Function Type R 4 R 8 INTE INTE INTE INTE QQ R 8 INTEGER Memory None of these functions are part of the FORTRAN 77 Standard Specific Name Argument Type Any INTEGER 4 INTEGER 8 Any Any expression LOC MALLOC MALLOC64 FREE SIZEOF TABLE 6 8 Memory Functions Intrinsic Definition No Function of Args Location Address of
176. e IF level as the ELSE must appear before Chapter4 Statements 137 IF or ELSE statement at the same IF level ELSE A matching any Examples Example 1 ELSE CHARACTER S IF 5 GE 0 AND 5 LE 9 THEN CALL PUSH ELSE CALL TOLOWER END IF Example 2 An invalid ELSE IF where an END IF is expected IF GT 5 THEN SE IF EQ 5 THEN Incorrect 138 FORTRAN 77 Language Reference May 2000 ELSE IF IF provides a multiple alternative decision structure THEN e2 THEN ELSE IF e1 END IF ELSE The TE where e1 and e2 are logical expressions Description You can make a series of independent tests and each test can have its own sequence of statements IF ELSE F block consists of all the executable statements following the END IF statement at IF e proceeds as follows depending on the value of the ELS IF ELSE T ELSE An statement up to but not including the next the same IF level as the ELSE IF statement F block can be empty ELSE ELSE An Execution of the logical expression e e is evaluated If e is true executio
177. e comma can be omitted anywhere the meaning is clear without it but other than those cases listed above this is nonstandard u Variable Format Expressions In general any integer constant in a format can be replaced by an arbitrary expression enclosed in angle brackets 1 FORMAT Be SES ig A The n in an nH edit descriptor cannot be a variable format expression Restrictions The FORMAT statement label cannot be used in a GO TO IF arithmetic DO or alternate return Warnings For explicit formats invalid format strings cause warnings or error messages at compile time For formats in variables invalid format strings cause warnings or error messages at runtime For variable format expressions of the form lt e gt invalid format strings cause warnings or error messages at compile time or runtime See Runtime Formats on page 305 for details Chapter4 Statements 9 Examples Example 1 Some A I and F formats READ 2 1 PART ID HEIGHT WEIGHT 1 FORMAT A8 2X 14 F8 2 F8 2 WRITE 9 2 PART ID HEIGHT WEIGHT FORMAT Part A8 Id 14 Height F8 2 amp Weight F8 2 DO 100 N FORMAT 2X F lt N 1 gt 2 160 FORTRAN 77 Language Reference May 2000 FUNCTION External The FUNCTION statement identifies a program unit as a function subprogram type FUNCTION fun ar ar Parameter Description type B
178. e keyword UNIT The unit parameter must be first namelist specifier must be second and there must not be a format specifier FORTRAN 77 Language Reference May 2000 318 The READ can have the form of the following example READ UNIT 1 NML CASE Data Syntax The first record of NAMELIST input data has the special symbol dollar sign in column two or beyond followed by the NAMELIST group name This is followed by a series of assignment statements starting in or after column two on the same or subsequent records each assigning a value to a variable or one or more values to array elements of the specified group The input data is terminated with another in or after column two as in the pattern ASgroup name variable value variable value END You can alternatively use an ampersand 6 in place of each dollar sign but the beginning and ending delimiters must match END is an optional part of the last delimiter The input data assignment statements must be in one of the following forms variable value array valuel value2 array subscript valuel value2 array subscript subscript value1 value2 variable character constant variable index index character constant If an array is subscripted it must be subscripted with the appropriate number of subscripts 1 2 3 Use quotes either
179. e literal constant For example 12 48 specifies an 8 byte integer constant value 12 12 6 specifies a 16 byte real constant value 2 1 345E 10_8 specifies an 8 byte real constant value 1 345E 10 1 5_8 895E 3_8 specifies a complex constant with 8 byte real and imaginary parts With complex constants the real and imaginary parts may be specified with different kind type parameters 1 0_8 2 0_4 but the resulting data item will have the real and imaginary parts with the same size taking the larger one specified This construction is valuable when calling subprograms with constant arguments when a specific data type is required as in the following example call suby A 1 5_8 0_8 Y subroutine suby H0 W INTEGER 8 Variables A variable is a symbolic name paired with a storage location A variable has a name a value and a type Whatever datum is stored in the location is the value of the variable This does not include arrays array elements records or record fields so this definition is more restrictive than the usual usage of the word variable You can specify the type of a variable in a type statement If the type is not explicitly specified in a type statement it is implied by the first letter of the variable name either by the usual default implied typing or by any implied typing of IMPLICIT statements See Types on page 23 for more details on th
180. e rules for data typing At any given time during the execution of a program a variable is either defined or undefined If a variable has a predictable value it is defined otherwise it is undefined A previously defined variable may become undefined as when a subprogram is exited You can define a variable with an assignment statement an input statement or a DATA statement If a variable is assigned a value in a DATA statement then it is initially defined Chapter 2 Data Types and Data Items 7 Two variables are associated if each is associated with the same storage location You can associate variables by use of EQUIVALENCE COMMON or MAP statements Actual and dummy arguments can also associate variables Arrays An array is a named collection of elements of the same type It is a nonempty sequence of data and occupies a group of contiguous storage locations An array has a name a set of elements and a type An array name is a symbolic name for the whole sequence of data An array element is one member of the sequence of data Each storage location holds one element of the array An array element name is an array name qualified by a subscript See Array Subscripts on page 51 for details You can declare an array in any of the following statements m DIMENSION statement m COMMON statement Type statements BYTE CHARACTER INTEGER REAL and so forth Array Declarators An array
181. eclarator The lower and upper limits of each dimension are designated by a dimension declarator The form of a dimension declarator is dd1 dd2 dd1 and dd2 are dimension bound expressions specifying the lower and upper bound values They can be arithmetic expressions of type integer or real They can be formed using constants symbolic constants formal arguments or variables defined in the COMMON statement Array references and references to user defined functions cannot be used in the dimension bound expression dd2 can also be an asterisk If dd1 is not specified a value of one is assumed The value of dd1 must be less than or equal to dd2 Nonconstant dimension bound expressions can be used in a subprogram to define adjustable arrays but not in a main program Noninteger dimension bound expressions are converted to integers before use Any fractional part is truncated Chapter4 Statements 123 Adjustable Array If the dimension declarator is an arithmetic expression that contains formal arguments or variables defined in the COMMON statement then the array is called an adjustable array In such cases the dimension is equal to the initial value of the argument upon entry into the subprogram Assumed Size Array The array is called an assumed size array when the dimension declarator contains an asterisk In such cases the upper bound of that dimension is not stipulated An asterisk can only appear for for
182. econd represents the imaginary part The default size for a COMPLEX item no size specified is 8 bytes The default alignment is on 4 byte boundaries However these defaults can be changed by compiling with certain special options see Size and Alignment of Data Types on page 31 FORTRAN 77 Language Reference May 2000 26 COMPLEX 8 The complex data type COMPLEX 8 is a synonym for COMPLEX except that it always has a size of 8 bytes independent of any compiler options COMPLEX 16 Double Complex The complex data type COMPLEX 16 is a synonym for DOUBLE COMPLEX except that it always has a size of 16 bytes independent of any compiler options COMP LEX 32 Quad Complex SPARC only The complex data type COMPLEX 32 is a quadruple precision complex It is a pair of REAL 16 elements where each has a sign bit a 15 bit exponent and a 112 bit fraction These REAL 16 elements in 77 conform to the IEEE standard The size for COMPLEX 32 is 32 bytes DOUBLE COMPLEX 8 The complex data type DOUBLE COMPLEX which usually has the synonym COMP LEX 16 is a pair of DOUBLE PRECISION REAL 8 values that represents a complex number The first element represents the real part the second represents the imaginary part The default size for DOUBLE COMPLEX with no size specified is 16 DOUBLE PRECISION A double precision datum is an approximation of a
183. ecursive function with implicit automatic INTEGER FUNCTION NFCTRL I IMPLICIT AUTOMATIC A Z RETUR D Local variables and arrays are static by default so in general there is no need to use SAVE You should use SAVE to ensure portability Also SAVE is safer if you leave a subprogram by some way other than a RETURN Restrictions Automatic variables and arrays cannot appear in DATA or SAVE statements FORTRAN 77 Language Reference May 2000 96 Arguments and function values cannot appear in DATA RECORD STATIC or SAVE statements because 77 always makes them automatic Examples Example Some other uses of AUTOMATIC UTOMATIC A B C EAL P D Q UTOMATIC P D Q PLICIT AUTOMATIC 2 HPD py Example Structures are unpredictable if AUTOMATIC demo cat autostru f AUTOMATIC X STRUCTURE ABC NTEGER I D STRUCTURE ECORD ABC X X is automatic It cannot be a structure 1 1 RINT END demo 77 silent autostru f demo a out TERMINATING a out Received signal 10 SIGBUS Bus Error core dumped demo H Ux DE 12 XAI Restrictions An AUTOMATIC statement and a type statement cannot be combined to make an AUTOMATIC type statement For example AUTOMATIC REAL X does not declare the variable X to be both AUTOMATIC and REAL it declares the variable REALX to be AUT
184. ed otherwise 115 an integer expression for the length in characters of each record of a file rl must be positive If the record length is unknown you can use RECL 1 see Direct Access I O on page 272 for more information If 1 6 is not set rl is number of characters and record length is rl If 1 lt 6 is set rl is number of words and record length is r 4 There are more details in the ACCESS SEQUENTIAL section above Each WRITE defines one record and each READ reads one record unread characters are flushed The default buffer size for tape is 64K characters For tapes we recommend the TOPEN routines because they are more reliable FORTRAN 77 Language Reference May 2000 200 ERR s The ERR s clause is optional s is a statement label of a statement to branch to if an error occurs during execution of the OPEN statement TOSTAT 108 The IOSTAT ios clause is optional ios is an integer variable that receives the error status from an OPEN After the execution of the OPEN if no error condition exists then ios is zero otherwise it is some positive number If you want to avoid aborting the program when an error occurs on an OPEN include ERR s or IOSTAT ios BLANK blnk The BLANK blnk clause is optional and is for formatted input only The bink is a character expression that indica
185. efault size for a declaration such as DOUBLE COMPLEX 2 can be altered by r8 xtypemap See the discussion in EAL 8 EX 16 Z the variable 2 is always two RI compiling with any of the options db1 Chapter 2 for details COMP LEX 16 For a declaration such as COMPLI elements contiguous in memory interpreted as one double width complex number FORTRAN 77 Language Reference May 2000 134 Comments There is a double complex version of each complex built in function Generally the specific function names begin with Z or CD instead of C except for the two functions DIMAG and DREAL which return a real value Examples are SIN CSIN CDSIN Example Double complex scalars and arrays DOUBLE COMPLEX U V DOUBLE COMPLEX W 3 6 COMPLEX 16 X Y 5 5 COMPLEX U 16 5 V 5 16 Chapter4 Statements 135 DOUBLE PRECISION The DOUBLE PRECISION statement specifies the type to be double precision and optionally specifies array dimensions and initializes with values DOUBLE PRECISION v c v c Parameter Description v Name of a symbolic constant variable array array declarator function or dummy function c List of constants for the immediately preceding name Description The declaration can be DOUBLE PRECISION or REAL 8 DOUBLE PRECISION For a declaration such as DOUBLE PRECISIO
186. em cannot tell UNIT u wu is an integer expression or with the value of the unit Exactly one of FILE or UNIT must be used FORTRAN 77 Language Reference May 2000 184 Examples Example 1 Inquire by unit LOGICAL OK INQUIRE UNIT 3 OPENED OK IF OK CALL GETSTD 3 STDS Example 2 Inquire by file LOGICAL THERE INQUIRE FILE profile EXIST THERE IF THERE CALL GETPROFILE FC PROFILE CHARACTER FN 32 LOGICAL HASNAM INQUIRE 3 OF ED OK NAMED HASNAME E FN IF OK AND AME PRINT Filename FN Chapter4 Statements 185 INTEGER The INTEGER statement specifies the type to be integer for a symbolic constant variable array function or dummy function Optionally it specifies array dimensions and size and initializes with values INTEGER len v len c v len c Parameter Description v Name of a symbolic constant variable array array declarator function or dummy function len Either 2 4 or 8 the length in bytes of the symbolic constant variable array element or function c List of constants for the immediately preceding name Description The declarations can be INTEGER INTEGER 2 INTEGER 4 INTEGER 8 186 FORTRAN 77 Language Reference May 2000
187. ement control jumps to must be executable not DATA ENTRY FORMAT or INCLUDE Control cannot jump into a DO IF ELSE IF or ELSE block from outside the block FORTRAN 77 Language Reference May 2000 166 Example Example Computed GO TO GO TO 10 20 30 40 N 10 CONTINUE 20 CONTINUE 40 CONTINUE In the above example If N equals one then go to 10 If N equals two then go to 20 If N equals three then go to 30 If N equals four then go to 40 If N is less than one or N is greater than four then fall through to 10 Chapter4 Statements 167 GO TO Unconditional The unconditional GO TO statement transfers control to a specified statement GO TO s Parameter Description 5 Statement label of an executable statement Description Execution of the GO TO statement transfers control to the statement labeled s Restrictions s must be in the same program unit as the GO TO statement The statement control jumps to must be executable not a DATA ENTRY FORMAT or INCLUDE statement Control cannot jump into a DO IF ELSE IF or ELSE block from outside the block Example A 100 0 B 0 01 GO TO 90 90 CONTINUE FORTRAN 77 Language Reference May 2000 168 IF Arithmetic The arithmetic IF statement branches to one of three specified statements depending on the value of an arithmetic express
188. ent Restrictions Jumping into the range of a DO WHILE loop from outside its range can produce unpredictable results Comments The variables used in the e can be modified in any way within the range of the DO WHILE loop 132 FORTRAN 77 Language Reference May 2000 133 Statements Chapter 4 Examples Example 1 A DO WHILE without a statement number INTEGER A 4 4 C R 6 4 1 DO WHILE 060 GT R A C R 1 cC cCc 1 END DO Example 2 A DO WHILE with a statement number INTEGER A 4 4 C R DO 10 WHILE C NE A C R A C R C Ctl 10 CONTINUI L 8 DOUBLE COMPLEX The DOUBLE COMPLEX statement specifies the type to be double complex It optionally specifies array dimensions and size and initializes with values DOUBLE COMPLEX v c 6 Parameter Description v Name of a symbolic constant variable array array declarator function or dummy function c List of constants for the immediately preceding name COMPLEX COMPLEX 16 COMPLEX zZ the variable 2 is two REA Description T The declaration can be DOUBLE DOUBLE COMPLEX For a declaration such as DOUBLI elements contiguous in memory interpreted as one double width complex number If you do not specify the size a default size is used The d
189. er 4 Examples Example 1 Simple backspace LUNIT BACKSPACE LUNIT 2 BACKSPACE Example 2 Backspace with error trap 2 IOSTAT CODE ERR 9 9 WRITE Error during BACKSPACE INTEGER CODE BACKSPACE STOP BLOCK DATA The BLOCK DATA statement identifies a subprogram that initializes variables and arrays in labeled common blocks BLOCK DATA name Parameter Description name Symbolic name of the block data subprogram in which the BLOCK DATA statement appears This parameter is optional It is a global name Description A block data subprogram can contain as many labeled common blocks and data initializations as desired The BLOCK DATA statement must be the first statement in a block data subprogram The only other statements that can appear in a block data subprogram are COMMON DATA DIMENSION D QUIVALENCE PLICIT PARAMETER ECORD SAVE STRUCTURE Type statements z i H Only an entity defined in a labeled common block can be initially defined in a block data subprogram If an entity in a labeled common block is initially defined all entities having storage units in the common block storage sequence must be specified even if they are not all initially defined FORTRAN 77 Language Reference May 2000 100 Restrictions Only one unnamed block data subpr
190. er format specifiers If a runtime format specifier is not of type CHARACTER the compiler accepts that too even though the FORTRAN Standard requires the CHARACTER type Omitted arguments in subprogram calls The compiler accepts omitted actual argument in a subroutine call that is two consecutive commas compile to a null pointer Reference to that dummy argument gives a segmentation fault FORTRAN 77 Language Reference May 2000 372 m REAL 16 SPARC only The compiler treats variables of type REAL 16 as quadruple precision Noncharacter variables The FORTRAN Standard requires the FILE specifier for OPEN and INQUIRE to be an expression of type CHARACTER 77 accepts a numeric variable or array element reference Consecutive operators 77 allows two consecutive arithmetic operators when the second operator is a unary or Here are two consecutive operators A B The above statement is treated as follows Illegal real expressions When the compiler finds a REAL expression where it expects an integer expression it truncates and makes a type conversion to INTEGER Examples Contexts for illegal real expressions that 77 converts to integer Alternate RETURN Dimension declarators and array subscripts Substring selectors Computed 60 TO Logical unit number record number and record length Typeless numeric constants Binary hexa
191. er4 Statements 155 Examples Example 1 Use your own version of TAN EXTERNAL TAN T TAN 45 0 FUNCTION TAN RETURN Example 2 Pass a user defined function name as an argument REAL AREA LOW HIGH EXTERNAL FCN CALL RUNGE FCN LOW HIGH AREA END FUNCTION FCN RETURN END SUBROUTINE RUNGE F 0 X1 A RETURN END FORTRAN 77 Language Reference May 2000 156 FORMAT The FORMAT statement specifies the layout of the input or output records label FORMAT f Parameter Description label Statement number f Format specification list The items in f have the form r desc r An optional repeat factor desc An edit descriptor If r is present then desc must be a repeatable edit descriptor The repeatable edit descriptors are E F E D G Iw Fw Ew Dw Gw Iw d Fw d Ew d Dw d Gw d 0 A Ew d e Dw d e Gw d e Ow Aw Eew dE Dw dEe Gw dEe ow d L 2 Lw ZW Zw d Here is a summary I O Z are for integers decimal octal hex F E D G are for reals fixed point exponential double general A is for characters L is for logicals The nonrepeatable edit descriptors are ala2 an single quote delimited character string 0102 an double quote delimited character string nHala2 an Hollerith string
192. es SPARC sont bas s sur une architecture d velopp e par Sun Microsystems Inc L interface d utilisation graphique OPEN LOOK et Sun a t d velopp e par Sun Microsystems Inc pour ses utilisateurs et licenci s Sun reconna t les efforts de pionniers de Xerox pour la recherche et le d veloppement du concept des interfaces d utilisation visuelle ou graphique pour l industrie de l informatique Sun d tient une licence non exclusive de Xerox sur l interface d utilisation graphique Xerox cette licence couvrant galement les licenci s de Sun qui mettent en place l interface d utilisation graphique OPEN LOOK et quien outre se conforment aux licences crites de Sun Sun 190 195 est deriv de CRAY CF90 un produit de Silicon Graphics Inc CETTE PUBLICATION EST FOURNIE EN L ETAT ET AUCUNE GARANTIE EXPRESSE OU IMPLICITE N EST ACCORDEE Y COMPRIS DES GARANTIES CONCERNANT LA VALEUR MARCHANDE L APTITUDE DE LA PUBLICATION A REPONDRE A UNE UTILISATION PARTICULIERE OU LE FAIT QU ELLE NE SOIT PAS CONTREFAISANTE DE PRODUIT DE TIERS CE DENI DE GARANTIE NE S APPLIQUERAIT PAS DANS LA MESURE OU IL SERAIT TENU JURIDIQUEMENT NUL ET NON AVENU Gd tem Ca Adobe PostScript Important Note New Product Names As part of Sun s new developer product strategy we have changed the names of our development tools from Sun WorkShop to Forte Developer products The products as you can see are the same high quality products
193. ess assignment pointers 65 malloc 65 adjustable array bounds 50 alignment structures as in VMS 376 378 summary of data types 31 allowed I O combinations 265 alternate octal notation 39 return 233 374 ampersand alternate return 103 105 374 Index 381 Index SYMBOLS 1 19 14 edit descriptor 279 NAMELIST delimiter 319 ESCR 374 LL 58 245 LOC 374 EF 374 L 374 amp 103 105 319 374 374 34 107 109 374 alternate return 103 105 comments 19 280 9 A blank character 276 304 312 concatenate string 76 H 3 JP X X gt D array bounds 49 character constants 36 edit descriptor 304 substring operator 54 lt gt 13 0 91 322 m 12 asterisk alternate return 103 374 hex and octal output 289 AUTOMATIC 96 automatic structure not allowed 97 B B constant indicator 43 format specifier 278 backslash 13 34 375 377 BACKSPACE 98 backspace character 36 basic terms 12 binary constants 43 I O 310 initialization 43 operator 70 binary file 200 bit and byte order 369 manipulation functions 336 346 operators 74 blank column one 267 313 control 278 field in octal or hex input 288 fields in octal or hex input 289 line comments 19 not significant in words 15 BLANK OPEN specifier 201 LOCK DATA 100 initialize 372 names 14 block IF 170 BN f
194. essions Operators and Operands An expression is a combination of one or more operands zero or more operators and zero or more pairs of parentheses There are three kinds of expressions m An arithmetic expression evaluates to a single arithmetic value m A character expression evaluates to a single value of type character a A logical or relational expression evaluates to a single logical value The operators indicate what action or operation to perform The operands indicate what items to apply the action to An operand can be any of the following kinds of data items Constant Variable Array element Function Substring Structured record field if it evaluates to a scalar data item An expression 69 Arithmetic Expressions An arithmetic expression evaluates to a single arithmetic value and its operands have the following types indicates a nonstandard feature BYTE m COMPLEX m COMPLEX 32 SPARC only DOUBLE COMPLEX DOUBLE PRECISION m INTEGER LOGICAL REAL REAL 16 SPARC only The operators for an arithmetic expression are any of the following TABLE 3 1 Arithmetic Operators Operator Meaning kk Exponentiation Multiplication Division Subtraction or Unary Minus Addition or Unary Plus If BYTE or LOGICAL operands are combined with arithmetic operators they are interpreted as integer data Each of these operators
195. f bytes These record sizes apply to direct access unformatted files only VMS style logical file names If the x1 d option is set then the compiler interprets VMS logical file names on the INCLUDE statement if it finds the environment variable LOGICALNAMEMAPP ING to define the mapping between the logical names and the UNIX path name You set the environment variable to a string of the form Inamel path1 Iname2 path2 Remember these rules for VMS style logical file names a Each Iname is a logical name and each path1 path2 and so forth is the path name of a directory without a trailing It ignores all blanks when parsing this string It strips any trailing no list from the file name in the INCLUDE statement Logical names in a file name are delimited by the first in the VMS file name FORTRAN 77 Language Reference May 2000 376 It converts file names from Inamel1 file to the path1 file form a For logical names uppercase and lowercase are significant If a logical name is encountered on the INCLUDE statement which is not specified in the LOGICALNAMEMAPP ING the file name is used unchanged Quote character introducing octal constants If the x1 d compiler option is on a VMS FORTRAN octal integer constant is treated as its decimal form Example VMS octal integer constant JCOUNT ICOUNT 703 The above statement i
196. for you It may be a useful feature if you Chapter 2 Data Types and Data Items 7 want to make one or more fields that you cannot reference in some particular subroutine The only thing that sF ILL does is provide a field of the specified size and type and preclude referencing it a You must explicitly type all field names The IMPLICIT statement does not apply to statements in a STRUCTURE declaration nor do the implicit I J K L M N rules apply m You cannot use arrays with adjustable or assumed size in field declarations nor can you include passed length CHARACTER declarations In a structure declaration the offset of field n is the offset of the preceding field plus the length of the preceding field possibly corrected for any adjustments made to maintain alignment See Data Representations on page 365 for a summary of storage allocation Record Declaration The RECORD statement declares variables to be records with a specified structure or declares arrays to be arrays of such records The syntax of a RECORD statement is RECORD structure name record list structure name record list structure name record list structure name Name of a previously declared structure record list List of variables arrays or arrays with dimensioning and index ranges separated by commas Example A RECORD that uses the previous STRUCTURE example R
197. g the delimiting quotes Within the field two consecutive quotes with no intervening blanks are counted as a single quote You can use apostrophes in a similar way Example quote f two equivalent ways WRITE 1 1 FORMAT This is a quote WRITE 2 2 FORMAT This is a quote END This program writes this message twice This is a quote Chapter5 Input and Output 3 Radix Control R The format specifier is R or nR where 2 gt n lt 36 If n is omitted the default decimal radix is restored You can specify radixes other than 10 for formatted integer I O conversion The specifier is patterned after P the scale factor for floating point conversion It remains in effect until another radix is specified or format interpretation is complete The I O item is treated as a 32 bit integer Example Radix 16 the format for an unsigned hex integer 10 places wide zero filled to 8 digits is su 162 110 8 asin demo cat radix f integer i 110 write 1 i 1 format SU 16 110 8 end demo 77 silent radix f demo a out AA0000006E demo SU is described in Sign Editing SU SP SS S on page 303 Editing REAL Data D E F G The D E F and G specifiers are for decimal real data items D Editing The D specifier is for the exponential form of decimal double precision items The general form is
198. gram Units A program unit is a sequence of statements terminated by an END statement Every program unit is either a main program or a subprogram If a program is to be executable it must have a main program There are three types of subprograms subroutines functions and block data subprograms The subroutines and functions are called procedures which are invoked from other procedures or from the main program The block data subprograms are handled by the loader Statements A statement consists of one or more key words symbolic names literal constants and operators with appropriate punctuation In FORTRAN no keywords are reserved in all contexts Most statements begin with a keyword the exceptions are the statement function and assignment statements Executable and Nonexecutable Statements Every statement is either executable or nonexecutable In general if a statement specifies an action to be taken at runtime it is executable Otherwise it is nonexecutable The nonexecutable statements specify attributes such as type and size determine arrangement or order define initial data values specify editing instructions define statement functions classify program units and define entry points In general nonexecutable statements are completed before execution of the first executable statement FORTRAN 77 Language Reference May 2000 16 FORTRAN Statements TABLE 1 4 FORTRAN Statements ACC
199. h of the symbolic constant The CHARACTER statement must appear before the PARAMETER statement Any symbolic name of a constant that appears in an expression e must have been defined previously in the same or a different PARAMETER statement in the same program unit The Sun WorkShop FORTRAN 77 compiler extends the PARAMETER statement to accept any expression including non constant expressions The statement will get a warning message to indicate that it is non standard and the value will be determined at runtime wherever the symbol is referenced However if the symbol defined in a PARAMETER statement with a non constant expression appears in a statement where a constant is expected such as a DATA statement it will get an error Restrictions A symbolic constant must not be defined more than once in a program unit If a symbolic name appears in a PARAMETER statement then it cannot represent anything else in that program unit A symbolic name cannot be used in a constant format specification but it can be used in a variable format specification If you pass a parameter as an argument and the subprogram tries to change it you may get a runtime error Examples Example 1 Some real character and logical parameters CHARACTER HEADING 10 LOGICAL T PARAMETER EPSILON 1 0E 6 PI 3 141593 HEADING IO Error amp T TRUE 208 FORTRAN 77 Language Refe
200. h w The value is right justified in that field The field consists of zero or more leading blanks followed by either a minus if the value is negative or an optional plus followed by a zero a decimal point the magnitude of the value of the list item rounded to d decimal digits and an exponent For the form Ew d If exponent gt 99 it has the form Enn or Onn If 99 lt exponent gt 999 it has the form nnn For the form Ew dEe if exponent lt 10 1 then the exponent has the form nnn For the form Dw d If exponent gt 99 it has the form Dnn or Enn or Onn If 99 lt exponent gt 999 it has the form nnn n is any digit The sign in the exponent is required w need not allow for a minus sign but must allow for a zero the decimal point and d digits to the right of the decimal point and an exponent Therefore for nonnegative numbers w lt d 6 if e is present then w lt d e 4 For negative numbers w lt d 7 if e is present then w lt d e 5 296 FORTRAN 77 Language Reference May 2000 Example Real input with editing in the program Einp f HARACTER L 40 1234567E2 1234 67E 3 12 4567 Q READ L E9 3 E12 3 E12 6 R S T PRINT E15 6 E15 6 E15 7 Ry S T END The above program displays AAAO 123457E 0 6AAA0 123467E 01AA0 1245670E 02 In the above
201. hat appears in the same program unit A character expression or integer array that specifies the format string The integer array is nonstandard Output List iolist can be empty or can contain output items or implied DO lists The output items must be one of the following Variables Substrings Arrays Array elements Record fields Chapter4 Statements 217 Any other expression A simple unsubscripted array name specifies all of the elements of the array in memory storage order with the leftmost subscript increasing more rapidly Implied DO lists are described on Implied Do Lists on page 119 Namelist Directed PRINT The second form of the PRINT statement is used to print the items of the specified namelist group Here grname is the name of a group previously defined by a NAMELIST statement Execution proceeds as follows The format if specified is established If the output list is not empty data is transferred from the list to standard output If a format is specified data is edited accordingly In the second form of the PRINT statement data is transferred from the items of the specified namelist group to standard output Restrictions Output from an exception handler is unpredictable If you make your own exception handler do not do any FORTRAN output from it If you must do some then call abort right after the output Doing so reduces the relative risk of a program freeze FORT
202. he main program The name of the program cannot be m The same as that of an external procedure or common block MAIN all uppercase or a runtime error results The name of the program can be the same as a local name in the main program The FORTRAN 77 Standard does not allow this practice Example Example A PROGRAM statement PROGRAM US_ECONOMY NVARS 2 NEQS 2 FORTRAN 77 Language Reference May 2000 220 READ The READ statement reads data from a file or the keyboard to items in the list Note Use the TOPEN routines to read from tape devices See the Fortran Library Reference Manual READ UNIT u FMT f IOSTAT ios REC rn END s ERR s iolist READ f iolist READ UNIT u NML grname IOSTAT i0s END s ERR s READ grname Parameter Description u Unit identifier of the unit connected to the file f Format identifier ios I O status specifier rn Record number to be read s Statement label for end of file processing iolist List of variables grname Name of a namelist group An alternate to the UNIT u REC rn form is as follows READ u rn iolist The options can be specified in any order Description EAD statement accepts the following arguments Identifier The RI Unit u is either an external unit identifier or an internal file identifier Chapter4 Statements 221
203. iated with any file has no effect Likewise RI terminal file has no effect either Using a REWIND statement on a direct access file is not defined in the FORTRAN 77 Standard and is unpredictable Chapter4 Statements 235 Examples Example 1 Simple form of unit specifier DFILE 3 REWIND 3 READ 3 12 I REWIND 3 READ 3 12 I Example 2 REWIND with the UNIT u form of unit specifier and error trap INTEGER CODE REWIND UNIT 3 REWIND UNIT 3 IOSTAT CODE ERR 100 100 WRITE error in rewinding STOP 236 FORTRAN 77 Language Reference May 2000 SAVE The SAVE statement preserves items in a subprogram after the RETURN or END statements are executed preventing them from becoming undefined SAVE v VvV m Parameter Description v Name of an array variable or common block enclosed in slashes occurring in a subprogram Description SAVE variables are placed in an internal static area All common blocks are already preserved because they have been allocated to a static area Therefore common block names specified in SAVE statements are allowed but ignored A SAVE statement is optional in the main program and has no effect 7J A SAVE with no list preserves all local variables and arrays in the routine Local variables and arrays are already static by default predisposing the need for
204. iated with corresponding dummy arguments The expression 6 the body of a statement function is evaluated If the type of the above result is different from the type of the function name then the result is converted Return the value The resulting value is thus available to the expression that referenced the function Chapter4 Statements 239 Restrictions Note these restrictions A statement function must appear only after the specification statements and before the first executable statement of the program unit in which it is referenced A statement function is not executed at the point where it is specified It is executed as any other by the execution of a function reference in an expression The type conformance between fun and e are the same as those for the assignment statement The type of fun and e can be different in which case e is converted to the type of fun The actual arguments must agree in order number and type with corresponding dummy arguments If a dummy argument is defined as a structure the corresponding actual argument must be similarly defined as the same structure A dummy argument cannot be an array or function name or have the same name as the function The same argument cannot be specified more than once in the argument list The statement function may be referenced only in the program unit that contains it The name of a statement function cannot be an actual argument Nor
205. ignent l utilisation la copie la distribution et la d compilation Aucune partie de ce produit ou document ne peut tre reproduite sous aucune forme par quelque moyen que ce soit sans l autorisation pr alable et crite de Sun et de ses bailleurs de licence s il y en a Le logiciel d tenu par des tiers et qui comprend la technologie relative aux polices de caract res est prot g par un copyright et licenci par des fournisseurs de Sun Des parties de ce produit pourront tre d riv es des syst mes Berkeley BSD licenci s par l Universit de Californie UNIX est une marque d pos e aux Etats Unis et dans d autres pays et licenci e exclusivement par X Open Company Ltd La notice suivante est applicable a Netscape Netscape Navigator et the Netscape Communications Corporation logo Copyright 1995 Netscape Communications Corporation Tous droits r serv s Sun Sun Microsystems the Sun logo docs sun com AnswerBookz2 Solaris SunOS JavaScript SunExpress Sun WorkShop Sun WorkShop Professional Sun Performance Library Sun Performance WorkShop Sun Visual WorkShop et Forte sont des marques de fabrique ou des marques d pos es ou marques de service de Sun Microsystems Inc aux Etats Unis et dans d autres pays Toutes les marques SPARC sont utilis es sous licence et sont des marques de fabrique ou des marques d pos es de SPARC International Inc aux Etats Unis et dans d autres pays Les produits portant les marqu
206. implicit typing are described here 174 FORTRAN 77 Language Reference May 2000 Implicit Typing The IMPLICIT statement can also indicate that no implicit typing rules apply in a program unit An IMPLICIT statement specifies a type and size for all user defined names that begin with any letter either a single letter or in a range of letters appearing in the specification An IMPLICIT statement does not change the type of the intrinsic functions An IMPLICIT statement applies only to the program unit that contains it A program unit can contain more than one IMPLICIT statement IMPLICIT types for particular user names are overridden by a type statement Note Compiling with any of the options db1 12 r8 or xt ypemap can alter the assumed size of names typed with an IMPLICIT statement that does not specify a size IMPLICIT REAL A Z See Chapter 2 and the Fortran User s Guide for details No Implicit Typing The second form of IMPLICIT specifies that no implicit typing should be done for user defined names and all user defined names shall have their types declared explicitly If either IMPLICIT NONE IMPLICIT UNDEFINED A Z is specified there cannot be any other IMPLICIT statement in the program unit Restrictions IMPLICIT statements must precede all other specification statements The same letter can appear more than once as a single letter or in a range of letters in all I
207. inate the program After you type go execution continues as if a CONTINUE statement is executed See this example demos cat p f PRINT Start PAUSE 1 PRINT Ok END demos 77 p f silent demo a out Start PAUSE 1 To resume execution type go Any other input will terminate the program go Execution resumed after 1 Ok demo 210 FORTRAN 77 Language Reference May 2000 If stdin is not a tty I O device PAUSE displays a message like this PAUSE To resume execution type kill 15 pid where pid is the process ID Example stdin not a tty I O device demo a out lt mydatafile PAUSE To resume execution type kill 15 20537 demo For the above example type the following command line at a shell prompt in some other window The window displaying the message cannot accept command input demo kill 15 20537 Chapter4 Statements 211 POINTER The POINTER statement establishes pairs of variables and pointers POINTER pl v1 p2 02 Parameter Description v1 v2 Pointer based variables also called pointees p1 p2 Corresponding pointers Description Each pointer contains the address of its paired variable A pointer based variable or pointee is a variable paired with a pointer in a POINTER statement A pointer based variable is usually called just a based variable The pointer is the integer variable
208. including the terminal statement If a DO statement appears within the range of another DO loop its range must be entirely contained within the range of the outer DO loop More than one labeled DO loop can have the same terminal statement If a DO statement appears within an IF ELSE IF or ELSE block the range of the associated DO loop must be contained entirely within that block If a block IF statement appears within the range of a DO loop the corresponding END IF statement must also appear within the range of that DO loop Block DO Loop A block Do loop consists of m DO statement Set of executable statements called a block Terminal statement an END DO statement This loop is nonstandard Execution proceeds as follows The expressions e1 e2 and e3 are evaluated If e3 is not present its value is assumed to be one Chapter4 Statements 127 The DO variable is initialized with the value of e1 The iteration count is established as the value of the expression MAX INT 62 61 e3 e3 0 The iteration count is zero if either of the following is true m el gt e2 and e3 gt zero el gt 62 and e3 lt zero If the onetrip compile time option is specified then the iteration count is never less than one The iteration count is tested and if it is greater than zero the range of the DO loop is executed Terminal Statement Pro
209. ing a plus sign depends on the implementation but 77 omits the plus sign The following sign specifiers are available SP If SP precedes a specification a sign is printed SS If SS precedes a specification plus sign printing is suppressed S lIf S precedes a specification the system default is restored The default is ss SU If SU precedes a specification integer values are interpreted as unsigned This is nonstandard Chapter5 Input and Output 303 For example the unsigned specifier can be used with the radix specifier to format a hexadecimal dump as follows 2000 FORMAT SU 16R 8110 8 The rules and restrictions for sign control are m Sign control specifiers apply to output only A sign control specifier remains in effect until another sign control specifier is encountered or format interpretation is complete The 5 SP and SS specifiers affect only I F E D and G editing m The SU specifier affects only I editing Slash Editing The slash edit specifier indicates the end of data transfer on the current record Sequential Access On input any remaining portion of the current record is skipped and the file is positioned at the beginning of the next record Two successive slashes skip a whole record On output an end of record is written and a new record is started Two successive slashes produce a record of no characters If the file i
210. ing field plus the length of the preceding field possibly corrected for any adjustments made to maintain alignment You can initialize a field that is a variable array substring substructure or union Chapter4 Statements 245 Examples Example 1 A structure of five fields STRUCTURE PRODUCT TEGER 4 ID 99 CHARACTER 16 NAME CHARACTER 8 MODEL Z REAL 4 COST REAL 4 PRICE END STRUCTURE ECORD PRODUCT CURRENT PRIOR NEXT LINE 10 In the above example a structure named PRODUCT is defined to consist of the fields ID NAME MODEL COST and PRICE Each of the three variables CURRENT PRIOR and NEXT is a record which has the PRODUCT structure and LINE is an array of 10 such records Every such record has its ID initially set to 99 and its MODEL initially set to Z Example 2 A structure of two fields STRUCTURE VARLENSTR INTEGER 4 NBYTES CHARACTER A 25 END STRUCTURE ECORD VARLENSTR VLS VLS NBYTES 0 246 FORTRAN 77 Language Reference May 2000 SUBROUTINE The SUBROUTINE statement identifies a named program unit as a subroutine and specifies arguments for it SUBROUTINE sub d d Parameter Description sub Name of subroutine subprogram d Variable name array name record name or dummy proce
211. ing it is treated as T1 TLn Relative Columns This tab reads from the nth column to the left or writes to the nth column to the left If n is missing it is treated as TLO Chapter 5 Input and Output 9 TRn Relative Columns This tab reads from the nth column to the right or writes to the nth column to the right If n is missing it is treated as TRO nTt Relative Tab Stop This tab tabs to the next tab stop for both read and write If n is omitted this tab uses n 1 and tabs to the next tab stop This edit specifier is not standard FORTRAN 77 The rules and Restrictions for tabbing are Tabbing right beyond the end of an input logical record is an error m Tabbing left beyond the beginning of an input logical record leaves the input pointer at the beginning of the record Nondestructive tabbing is implemented for both internal and external formatted 1 0 Nondestructive tabbing means that tabbing left or right on output does not destroy previously written portions of a record Tabbing right on output causes unwritten portions of a record to be filled with blanks m Tabbing left requires that the logical unit allows a seek Therefore it is not allowed in I O to or from a terminal or pipe Likewise nondestructive tabbing in either direction is possible only on a unit that can seek Otherwise tabbing right or spacing with the X edit specifier writes blanks on the output m Tab stops are
212. ing statements COMMON DATA I O statements NAMELIST RECORD statements SAVE Type statements In an EQUIVALENCE statement the array name without subscripts indicates the first element of the array Array Subscripts An array element name is an array name qualified by a subscript Form of a Subscript A subscript is a parenthesized list of subscript expressions There must be one subscript expression for each dimension of the array Chapter 2 Data Types and Data Items 51 The form of a subscript is s s where s is a subscript expression The parentheses are part of the subscript Example Declare a two by three array with the declarator REAL M 2 3 With the above declaration you can assign a value to a particular element as follows M 1 2 0 0 The above code assigns 0 0 to the element in row 1 column 2 of array M Subscript Expressions Subscript expressions have the following properties and restrictions A subscript expression is an integer real complex logical or byte expression According to the FORTRAN Standard it must be an integer expression A subscript expression can contain array element references and function references Evaluation of a function reference must not alter the value of any other subscript expression within the same subscript m Each subscript expression is an index into the appropriate dimension of the array Each sub
213. ion The expression itself must be enclosed in angle brackets 306 FORTRAN 77 Language Reference May 2000 For example the 6 in 1 FORMAT 3F6 1 can be replaced by the variable N as in 1 FORMAT 3F lt N gt 1 or by the slightly more complicated expression 2 N M as in 1 FORMAT 3F lt 2 N M gt 1 Similarly the 3 or 1 can be replaced by any expression The single exception is the n in an nH edit descriptor The rules and restrictions for variable format expressions are The expression is reevaluated each time it is encountered in a format scan If necessary the expression is converted to integer type Any valid FORTRAN expression is allowed including function calls Variable expressions are not allowed in formats generated at runtime The n in an nH edit descriptor cannot be a variable expression Unformatted I O Unformatted I O is used to transfer binary information to or from memory locations without changing its internal representation Each execution of an unformatted I O statement causes a single logical record to be read or written Since internal representation varies with different architectures unformatted I O is limited in its portability You can use unformatted I O to write data out temporarily or to write data out quickly for subsequent input to another FORTRAN program running on
214. ion IF 6 81 s2 3 Parameter Description e Arithmetic expression integer real double precision or quadruple precision s1 s2 s3 Labels of executable statements Description The IF statement transfers control to the first second or third label if the value of the arithmetic expression is less than zero equal to zero or greater than zero respectively The restrictions are The s1 82 s3 must be in the same program unit as the IF statement The same statement label can appear more than once in a IF statement The statement control jumps to must be executable not DATA ENTRY FORMAT or INCLUDE Control cannot jump into a DO IF ELSE IF or ELSE block from outside the block Example IF 10 20 30 Since the value of N is zero control is transferred to statement label 20 Chapter4 Statements 169 IF Block The block IF statement executes one of two or more sequences of statements depending on the value of a logical expression IF e THEN END IF Parameter Description e A logical expression Description The block IF statement evaluates a logical expression and if the logical expression is true it executes a set of statements called the IF block If the logical expression is false control transfers to the next ELSE ELSE IF or END IF statement at the same IF level IF Level The IF level of a state
215. ion CHECK NO UNDERF LOW None not implemented CHECK NONE Disables the C option NOCHECK Disables the 6 option NO EXTEND_SOURCE Disables enables the 6 option Restrictions The OPTIONS statement must be the first statement in a program unit it must be before the BLOCK DATA FUNCTION PROGRAM and SUBROUTINE statements Options set by the OPTIONS statement override those of the command line Options set by the OPTIONS statement endure for that program unit only A qualifier can be abbreviated to four or more characters Uppercase or lowercase is not significant Chapter4 Statements 205 Example For the following source integer variables declared with no explicit size occupy 4 bytes rather than 2 with or without the 12 option on the command line This rule does not change the size of integer constants only variables OPTIONS 4 PROGRAM FFT END By way of contrast if you use NOT4 then all integer variables declared with no explicit size occupy 2 bytes rather than 4 with or without the 12 option on the command line However integer constants occupy 2 bytes with 12 and 4 bytes otherwise 206 FORTRAN 77 Language Reference May 2000 PARAMETER The PARAMETER statement assigns a symbolic name to a constant PARAMETER p e p e 4 Parameter Description p Symbolic name e Constant expression An alternate syntax is allowed if the x1 flag is set PARAMETE
216. ion 43 octal and hex format 287 format samples 288 input 287 input rules 288 output 288 289 offset of fields 58 245 omitted arguments 372 OPEN specifier ACCESS 199 BLANK 201 ERR 201 FILE 199 Index 9 OGICAL 2 29 OGICAL 4 29 OGICAL 8 30 long lines in source code 18 lower case 14 15 lrshft 343 M malloc 65 338 man pages 1 MANPATH environment variable 1 MAP 62 194 253 maximum number of open files 263 memory get by malloc 65 release by free 66 memory allocation and deallocation functions 338 mixed integer and logical 73 74 mode 72 73 mixed mode 73 mixing format of source lines 18 modifying carriage control 279 multithreading See parallelization N name of scratch files 201 NAME option for OPEN 374 NAMELIST 195 317 319 320 318 amp 319 ask for names 322 namelist specifier 317 NML 317 prompt for names 322 restrictions 316 WRITE 317 namelist data 319 322 POINTER 212 pointer 63 2 address assignment 65 address by LOC 65 212 disallowed in NAMELIST 316 linked list 215 problems with optimization 67 restrictions 66 VOLATILE 212 pointer based variable 66 316 positional edit descriptor 289 format editing 289 preattached files 269 logical units 269 precedence logical operator 80 operators 71 PRINT 217 print file 200 266 313 procedures 16 PROGRAM 220 program 12 names 14 units 1
217. is a binary operator in an expression of the form a b where a and b are operands and is any one of the or operators Examples Binary operators A Z X B FORTRAN 77 Language Reference May 2000 70 The operators and are unary operators in an expression of the form b where b is an operand and is either of the or operators Examples Unary operators Z B Basic Arithmetic Expressions Each arithmetic operator is shown in its basic expression in the following table TABLE 3 2 Arithmetic Expressions Expression Meaning a Proz Raise a to the power z a 2 Divide a by 2 a 2 Multiply a by z a z Subtract z from a Negate z 8 2 Add 2 toa 2 Same as 2 In the absence of parentheses if there is more than one operator in an expression then the operators are applied in the order of precedence With one exception if the operators are of equal precedence they are applied left to right TABLE 3 3 Arithmetic Operator Precedence Operator Precedence ae First Bef Second Last For the left to right rule the one exception is shown by the following example E k k 5 k k 2 Chapter 3 Expressions 1 The above is evaluated as x 5 k k Z 77 allows two successive operators Example Two successive operators xX FZ The above expression is evaluated as follows
218. l Characters Each character string constant appearing outside a DATA statement is followed by a null character to ease communication with C routines You can make character string constants consisting of no characters but only as arguments being passed to a subprogram Such zero length character string constants are not FORTRAN standard FORTRAN 77 Language Reference May 2000 34 35 Example Null character string demo cat NulChr f 0 7 taty tp Mb stop end demo 77 NulChr f NulChr f MAIN demo a out ab demo However if you put such a null character constant into a character variable the variable will contain a blank and have a length of at least 1 byte Example Length of null character string demo cat NulVar f characters tat Pp oY 7 Ef write 2 write len y end demo 77 NulVar f NulVar f MAIN demo a out ac 1 demo Chapter 2 Data Types and Data Items Escape Sequences For compatibility with C usage the following backslash escapes are recognized If you include the escape sequence in a character string then you get the indicated character TABLE 2 3 Backslash Escape Sequences Escape Sequence Character n Newline r Carriage return t Tab b Backspace f Form feed v Vertical tab 0 Null ye Apostrophe which does not terminate a string Quotation mark which does not terminate a string x x where x is any
219. l Restriction Do not reference a function in an I O list if executing that function causes an I O statement to be executed Example WRITE 1 10 Y A 2 0 F X Wrong if F does I O FORTRAN 77 Language Reference May 2000 264 Kinds of I O The kinds of I O supported by 77 are formatted unformatted binary list directed and NAMELIST The two modes of access to files are sequential and direct When you open a file the access mode is set to either sequential or direct If you do not set it explicitly you get sequential by default The two types of files are external files and internal files An external file resides on a physical peripheral device such as disk or tape An internal file is a location in main memory is of character type and is either a variable substring array array element or a field of a structured record Combinations of I O I O combinations on external files are Allowed Not Allowed Sequential unformatted Direct access list directed 0 Sequential formatted Direct access NAMELIST I O Sequential list directed NAMELIST I O on internal files Sequential NAMELIST Unformatted internal I O Direct unformatted Binary direct access Direct formatted Binary formatted Binary sequential unformatted The following table shows combinations of I O form access mode and physical file types TABLE 5 1 Summary of 77 Input and Output Kind of I O Access Mode Form File
220. l argument to be passed to the subroutine Description Arguments are separated by commas The FORTRAN 77 Standard requires that actual arguments in a CALL statement must agree in order number and type with the corresponding formal arguments of the referenced subroutine The compiler checks this only when the XlistE option is on Recursion is allowed A subprogram can call itself directly or indirectly by calling another subprogram that in turns calls this subroutine Such recursion is nonstandard An actual argument ar must be one of the following An expression m An intrinsic function permitted to be passed as an argument for a list of the intrinsics that cannot be actual arguments see TABLE 4 2 An external function name A subroutine name An alternate return specifier or amp followed by a statement number The is nonstandard The simplest expressions and most frequently used include such constructs as Constant Variable name Array name Formal argument if the CALL statement is inside a subroutine Record name Chapter4 Statements 103 If a subroutine has no arguments then a CALL statement that references that subroutine must not have any actual arguments A pair of empty matching parentheses can follow the subroutine name Execution of the CALL statement proceeds as follows 1 All expressions arguments are evaluated 2 All actual arguments are associated with the corres
221. l variables and arrays are classified static by default there is exactly one copy of each datum and its value is retained between calls You can also explicitly define variables as static or automatic in a STATIC or AUTOMATIC statement or in any type statement or IMPLICIT statement However you can still use STATIC to ensure portability especially with routines that leave a subprogram by some way other than a RETURN Also note that Arguments and function values are automatic m A STATIC statement and a type statement cannot be combined to make a STATIC type statement For example the statement STATIC REAL X does not declare the variable X to be both STATIC and REAL it declares the variable REALX to be STATIC Example ATIC A B C EAL P D Q ATIC P D Q PLICIT STATIC X Z 3 FORTRAN 77 Language Reference May 2000 242 SLOP The STOP statement terminates execution of the program STOP str Parameter Description str String of no more that 5 digits or a character constant Description The argument str is displayed when the program stops If str is not specified no message is displayed Examples Example 1 Integer stop 9 The above statement displays STOP 9 Example 2 Character stop error The above statement displays STOP error Chapter4 Statements 243 STRUCTURE The STRUCTURE statement organizes data into
222. ld consists of the characters up to but not including the comma the next field begins with the character following the comma Remaining Characters Q The Q edit descriptor gets the length of an input record or the remaining portion of it that is unread It gets the number of characters remaining to be read from the current record FORTRAN 77 Language Reference May 2000 300 Example From a real and a string get real string length and string demo cat qed1 f gedl f Q edit descriptor real amp string CHARACTER CVECT 80 1 OPEN UNIT 4 FILE qedl data READ 4 1 R L CVECT I I 1 L 1 FORMAT F4 2 Q 80 Al WRITE 6 2 Ryo Ly Ae GVECT AT Ly ye Rt 2 FORMAT 1X F7 2 1X 12 1X 8081 END demo cat 51 8 8 10qwerty demo 77 qed1 f 1 gedl f MAIN demo qedl 8 10 6 qwerty demo The above program reads a field into the variable R then reads the number of characters remaining after that field into L then reads L characters into CVECT Q as the nth edit descriptor matches with L as the nth element in the READ list Example Get length of input record put the Q descriptor first demo cat qed2 f CHARACTER CVECT 80 1 OPEN UNIT 4 FILE qed2 data READ 4 1 L CVECT I I 1 L 1 FORMAT Q 8021 WRITE 2 L CVECT I I 1 L
223. le 2 Initialize 4 2 1 2 4 V 1 INTEGER 188 FORTRAN 77 Language Reference May 2000 INTRINSIC The INTRINSIC statement lists intrinsic functions that can be passed as actual arguments INTRINSIC fun fun Parameter Description fun Function name Description If the name of an intrinsic function is used as an actual argument it must appear in an INTRINSIC statement in the same program unit Example Intrinsic functions passed as actual arguments INTRINSIC SIN COS CALC SIN COS Restrictions ERNAL and an INTRINSIC A symbolic name must not appear in both an EX statement in the same program unit The actual argument must be a specific name Most generic names are also specific but a few are not IMAG LOG and LOG10 A symbolic name can appear more than once in an INTRINSIC statement In the FORTRAN 77 Standard a symbolic name can appear only once in an INTRINSIC statement Chapter4 Statements 189 Because they are inline or generic the following intrinsics cannot be passed as actual AMIN1 DMIN1 IMIN1 JMIN1 QMIN1 IMAG LOG LOG10 QREAL QCMP LX SIZEOF EPBASE EPEMAX EPEMIN EPHUGE EPMRSP EPPREC EPTINY arguments TABLE 4 2 Intrinsics That Cannot Be Passed As Actual Arguments AIMAX0O AJMAX0 AXO AXO D G 0 lt 0 AX1
224. list of the OPEN specifier keywords UNIT m uis an integer expression or an asterisk that specifies the unit number u is required If u is first in the parameter list then UNIT can be omitted FORTRAN 77 Language Reference May 2000 198 FILE fin fin is a character expression naming the file to open An OPEN statement need not specify a file name If the file name is not specified a default name is created Reopening files If you open a unit that is already open without specifying a file name or with the previous file name FORTRAN thinks you are reopening the file to change parameters The file position is not changed The only parameters you are allowed to change are BLANK NULL or ZERO and FORM FORMATTED or PRINT To change any other parameters you must close then reopen the file Switching Files If you open a unit that is already open but you specify a different file name it is as if you closed with the old file name before the open Switching Units If you open a file that is already open but you specify a different unit that is an error This error is not detected by the ERR option however and the program does not terminate abnormally Scratch Files If a file is opened with STATUS SCRATCH a temporary file is created and opened See STATUS sta ACCESS acc The ACCESS acc clause is optional acc is a character expression Possible values are APPEND DIRECT or SEQUENTIAL The
225. ll arithmetic character relational and logical expressions If you reference any one of these items in an expression variable array element character substring record field pointer or function then that item must be defined at the time the reference is executed An integer operand must be defined with an integer value and not with a statement label value by an ASSIGN statement All the characters of a substring that are referenced must be defined at the time the reference is executed The execution of a function reference must not alter the value of any other entity within the same statement The execution of a function reference must not alter the value of any entity that affects the value of any other function reference in the same statement Chapter 3 Expressions 5 86 FORTRAN 77 Language Reference May 0 Statements This chapter describes the statements recognized by the Sun WorkShop FORTRAN 77 compiler 77 Nonstandard features are indicated by the symbol See Chapter 1 for a discussion of the conforming standards A table of sample statements appears in Appendix B 87 CHAPTER 4 ACCEPT The ACCEPT statement reads from standard input and requires the following syntax ACCEPT f iolist ACCEPT grname Parameter Description f Format identifier iolist List of variables substrings arrays and records grname Name of the namelist g
226. loop with a shared variable ED yvalue keyword Example Specifying a CSPAR DOALL SHAR See the Fortran Programming Guide for details about parallelization and these directives Fortran parallelization features require a Sun WorkShop HPC license Chapter 1 Elements of FORTRAN 21 22 FORTRAN 77 Language Reference May 2000 CHAPTER 2 Data Types and Data Items This chapter describes the data types and data structures in Sun FORTRAN 77 Nonstandard features are tagged with a small black cross Types Except for specifically typeless constants any constant constant expression variable array array element substring or function usually represents typed data On the other hand data types are not associated with the names of programs or subroutines block data routines common blocks namelist groups or structured records Rules for Data Typing The name determines the type that is the name of a datum or function determines its data type explicitly or implicitly according to the following rules of data typing A symbolic name of a constant variable array or function has only one data type for each program unit except for generic functions If you explicitly list a name in a type statement then that determines the data type If you do not explicitly list a name in a type statement then the first letter of the name determines the data type implicitly The default implicit typi
227. mal arrays and as the upper bound of the last dimension in an array declarator Examples Example 1 Arrays in a main program DIMENSION M 4 4 V 1000 END In the above example M is specified as an array of dimensions 4 x4 and V is specified as an array of dimension 1000 Example 2 An adjustable array in a subroutine SUBROUTINE INV DIMENSION END In the above example the formal arguments are an array M and a variable N M is specified to be a square array of dimensions Nx N Example 3 Lower and upper bounds DIMENSION HELIO 3 3 4 3 9 END FORTRAN 77 Language Reference May 2000 124 In the above example HELIO is a 3 dimensional array The first element is HELIO 3 1 3 and the last element is HELIO 3 4 9 Example 4 Dummy array with lower and upper bounds SUBROUTINE ENHANCE A NLO NHI DIMENSION A NLO NHI END Example 5 Noninteger bounds PARAMETER LO 1 HI 9 3 DIMENSION A HI HI 3 LO END In the above example A is an array of dimension 9x28 Example 6 Adjustable array with non integer bounds SUBROUTINE ENHANCE A X Y DIMENSION A X Y END Example 7 Assumed size arrays SUBROUTINE RUN A B N DIMENSION A Chapter4 Statements 125 DO The DO statement
228. mber of characters in the collating sequence and A is of type character of length one CHAR and ICHAR are inverses in the following sense ICHAR CHAR I I for 011 Chapter 6 Intrinsic Functions 1 m CHAR ICHAR C C for any character 0 capable of representation in the processor 6 COMPLEX A COMPLEX value is expressed as an ordered pair of reals ar ai where ar is the real part and ai is the imaginary part 7 Radians All angles are expressed in radians unless the Intrinsic Function column includes the degrees remark 8 COMPLEX Function The result of a function of type COMPLEX is the principal value 8 CBRT If a is of COMPLEX type CBRT results in COMPLEX RT1 A B where A 0 0 and 60 degrees lt arctan B A lt 60 degrees Other two possible results can be evaluated as follows RT2 RT1 0 5 square_root 0 75 RT3 RT1 0 5 square_root 0 75 9 Argument types All arguments in an intrinsic function reference must be of the same type 10 INDEX INDEX X Y is the place in X where Y starts That is it is the starting position within character string X of the first occurrence of character string Y If Y does not occur in X then INDEX 0 If LEN X gt LEN Y then INDEX X Y is 0 INDEX returns default INTEGER 4 data If compiling for a 64 bit environment the compiler will i
229. ment S is the value n1 n2 where n1 is the number of block IF statements from the beginning of the program unit up to the end including S n2 is the number of END IF statements in the program unit up to but not including 5 Example In the following program the IF level of statement 9 is 2 1 or 1 IF LT 0 0 THEN MIN NODE END IF 9 IF Y LT 0 0 THEN MIN NODE 1 END IF The IF level of every statement must be zero or positive The IF level of each block IF ELSE IF ELSE and END IF statement must be positive The IF level of the END statement of each program unit must be zero FORTRAN 77 Language Reference May 2000 170 IF Block An IF block consists of all the executable statements following the block IF statement up to but not including the next ELSE ELSE IF or END IF statement that has the same if level as the block IF statement An IF block can be empty In the following example the two assignment statements form an IF block END IF Execution proceeds as follows The logical expression e is evaluated first If e is true execution continues with the first statement of the IF block If e is true and the IF block is empty control is transferred to the next END IF statement with the same IF level as the block IF statement If e is false control is transferred to the next E
230. mple there are N M 1 characters in the substring Here are the rules and restrictions for substrings FORTRAN 77 Language Reference May 2000 54 Character positions within a substring are numbered from left to right The first character position is numbered 1 not 0 The initial and last character positions must be integer expressions If the first expression is omitted it is 1 If the second expression is omitted it is the declared length The result is undefined unless 0 lt I gt Ls the declared length where I is the initial position and L is the last position Substrings can be used on the left and right sides of assignments and as procedure actual arguments Substrings must not be overlapping ASTR 2 4 ASTR 3 5 is illegal Examples Substrings the value of the element in column 2 row 3 is e23 demo cat sub f character v 8 abcdefgh 621 611 amp m 2 3 3 e22 623 amp e12 amp erg print 3555 prin prin prin prin print prin Gh Gh eh orr act FF F F F F F F oN print print print print end demo 7 sub f MAIN demo cde abcdefgh abcdefgh abcdefgh ell e21 e12 e22 e13 e23 13 demo s83 RB 04 N N WWWNHNEF EF sub f a out Chapter 2 Data Types and Data Items 5 Structures A structure is
231. mpt for the C shell Bourne shell and Korn shell TABLE P 2 Shell Prompts Shell Prompt C shell oe Bourne shell and Korn shell 5 C shell Bourne shell and Korn shell superuser Related Documentation You can access documentation related to the subject matter of this book in the following ways Through the Internet at the docs sun com Web site You can search for a specific book title or you can browse by subject document collection or product at the following Web site http docs sun com Through the installed Sun WorkShop products on your local system or network Sun WorkShop 6 HTML documents manuals online help man pages component readme files and release notes are available with your installed Sun WorkShop 6 products To access the HTML documentation do one of the following In any Sun WorkShop or Sun WorkShop TeamWare window choose Help lt About Documentation In your Netscape Communicator 4 0 or compatible version browser open the following file opt SUNWspro docs index html Contact your system administrator if your Sun WorkShop software is not installed in the opt directory Your browser displays an index of Sun WorkShop 6 HTML documents To open a document in the index click the document s title Preface 5 TABLE P 3 lists related Sun WorkShop 6 manuals by document collection Related Sun WorkShop 6 Documentation by Document Collection Description
232. n the comment indicator character m The next 7 characters are PRAGMA no blanks any uppercase or lowercase Rules and Restrictions After the first eight characters blanks are ignored and uppercase and lowercase are equivalent as in FORTRAN text Because it is a comment a directive cannot be continued but you can have many CSPRAGMA lines one after the other as needed If a comment satisfies the above syntax it is expected to contain one or more directives recognized by the compiler if it does not a warning is issued Parallelization Directives Parallelization directives explicitly request the compiler attempt to parallelize the DO loop that follows the directive The syntax differs from general directives Parallelization directives are only recognized when compilation options parallel or explicitpar are used 77 parallelization options are described in the Fortran Programming Guide Parallelization directives have the following syntax FORTRAN 77 Language Reference May 2000 20 The first character must be in column one The first character can be any one of c C or The next four characters are PAR no blanks either upper or lower case rective keyword and options separated by blanks Next follows the di The explicit parallelization directive keywords are TASKCOMMON DOALL DOSERIAL and DOSERIAL Each parallelization directive has its own set of optional qualifiers that follow the
233. n WorkShop 6 Documentation by Document Collection Continued Description Describes the C compiler options Sun specific capabilities such as pragmas the Lint tool parallelization migration to a 64 bit operating system and ANSI ISO compliant C Describes the C libraries including C Standard Library Tools h class library Sun WorkShop Memory Monitor Iostream and Complex Provides guidance on migrating code to this version of the Sun WorkShop C compiler Explains how to use the new features to write more efficient programs and covers templates exception handling runtime type identification cast operations performance and multithreaded programs Provides information on command line options and how to use the compiler Describes how the Sun WorkShop Memory Monitor solves the problems of memory management in C and C This manual is only available through your installed product see opt SUNWspro docs index html and not at the docs sun com Web site Provides details about the library routines supplied with the Fortran compiler Preface 7 Document Title C User s Guide C Library Reference C Migration Guide C Programming Guide C User s Guide Sun WorkShop Memory Monitor User s Manual Fortran Library Reference Document Collection Forte C 6 Sun WorkShop 6 Compilers C Forte C 6 Sun WorkShop 6 Compilers C Forte for High Performance C
234. n WorkShop FORTRAN 77 Preface 3 Typographic Conventions TABLE P 1 shows the typographic conventions that are used in Sun WorkShop documentation Examples Edit your login file Use 1s a to list all files 9 You have mail su Password Read Chapter 6 in the User s Guide These are called class options You must be superuser to do this To delete a file type rm filename Typographic Conventions Meaning The names of commands files and directories on screen computer output What you type when contrasted with on screen computer output Book titles new words or terms words to be emphasized Command line placeholder text replace with a real name or value TABLE P 1 Typeface AaBbCc123 AaBbCc123 AaBbCc123 AaBbCc123 The symbol A stands for a blank space where a blank is significant AA36 001 Mo Standards are discussed in Nonstandard features are tagged with the symbol Chapter 1 m FORTRAN examples appear in tab format not fixed columns See the discussion of source line formats in the Fortran User s Guide for details The FORTRAN 77 standard uses an older convention of spelling the name FORTRAN capitalized Sun documentation uses both FORTRAN and Fortran The current convention is to use lower case Fortran 95 FORTRAN 77 Language Reference May 2000 4 Shell Prompts TABLE P 2 shows the default system prompt and superuser pro
235. n continues with the first statement of the ELSE IF block If e is true and the statement at the same IF level as the END IF IF statement SE END IF statement ELSE IF block E IF EL ELSE E IF block is empty control is transferred to the next ELS If e is false control is transferred to the next ELS at the same IF level as the ELSE IF statement Restrictions You cannot jump into an ELSE IF block from outside the IF statement cannot be referenced by any ELSE IF must appear 139 Statements statement of the same IF level as the ELSE statement at the same IF level Chapter 4 or IF TE The statement label if any of an ELSE statement A matching END ELSE before any Example Example ELSE IF in LT 0 THEN WRITE 0 gt SSE IF EQ 0 THEN WRITE N 0 EA U WRITE N gt 0O 140 FORTRAN 77 Language Reference May 2000 ENCODE DECODE The ENCODE statement writes data from a list to memory ENCODE size f buf IOSTAT ios ERR s iolist Parameter Description size Number of characters to be translated f Format identifier b
236. name FALSE otherwise Chapter4 Statements 3 NEXTREC nr nr is an integer variable that is assigned one plus the number of the last record read from a file connected for direct access If the file is not connect 1 is returned in nr NUMBER num num is an integer variable that is set to the number of the unit connected to the file if any If no file is connected num is set to 1 OPENED od m od is a logical variable that is set to TRUE if the file is connected to a unit or the unit is connected to a file and FALSE otherwise RECL rcl rclis an integer variable that is assigned the record length of the records in the file if the file is connected for direct access 77 does not adjust the rcl returned by INQUIRE The OPEN statement does such an adjustment if the x1 d option is set See Details of Features That Require x1 d on page 376 for an explanation of x1 d If no file is connected rcl is set to 1 SEQUENT IAL seq m seg is a character variable that is assigned the value YES if the file could be connected for sequential I O NO if the file could not be connected for sequential I O and UNKNOWN if the system can t tell UNFORMATTED unf unf is a character variable that is assigned the value YES if the file could be connected for unformatted I O No if the file could not be connected for unformatted I O and UNKNOWN if the syst
237. nction returns REAL 8 A call to a DOUBLE PRECISION function returns REAL 8 A call to a COMPLEX function returns COMPLEX 16 A call to a DOUBLE COMPLEX function returns COMPLEX 16 U Other options that alter the data sizes of default data types are r8 and 1 which also promote DOUBLE to QUAD The xt ypemap option provides more flexibility than these older compiler options and is preferred A function with a generic name returns a value with the same type as the argument except for type conversion functions the nearest integer function the absolute value of a complex argument and others If there is more than one argument they must all be of the same type If a function name is used as an actual argument then it must be a specific name If a function name is used as a dummy argument then it does not identify an intrinsic function in the subprogram and it has a data type according to the same rules as for variables and arrays Chapter 6 Intrinsic Functions 9 Notes Functions Tables and notes 1 through 12 are based on the Table of Intrinsic Functions from ANSI X3 9 1978 Programming Language FORTRAN with the FORTRAN extensions added 1 INT If A is type integer then INT A is A If A is type real or double precision then if A gt 1 then INT A is 0 if A lt 1 then INT A is the greatest integer that does not ex
238. nds of arithmetic constants Typed Constants Typeless Constants Complex Binary Double complex Octal Double precision Hexadecimal Integer Hollerith Real Chapter 2 Data Types and Data Items 3 A signed constant is an arithmetic constant with a leading plus or minus sign An unsigned constant is an arithmetic constant without a leading sign For integer real and double precision data zero is neither positive nor negative The value of a signed zero is the same as that of an unsigned zero Compiling with any of the options 12 601 28 or xt ypemap alters the default size of integer real complex and double precision constants These options are described in Chapter 2 and in the Fortran User s Guide Character Constants A character string constant is a string of characters enclosed in apostrophes or quotes The apostrophes are standard the quotes are not If you compile with the x1 option then the quotes mean something else and you must use apostrophes to enclose a string To include an apostrophe in an apostrophe delimited string repeat it To include a quote in a quote delimited string repeat it Examples abc abc Tain t in vi type If a string begins with one kind of delimiter the other kind can be embedded within it without using the repeated quote or backslash escapes See TABLE 2 3 Example Character constants abc ain t in vi type hgy Nul
239. ne the mapping between the logical names and the UNIX path name 77 uses the following rules for the interpretation The environment variable should be set to a string with the syntax Inamel path1 Iname2 path2 where each Iname is a logical name and each path1 path2 and so forth is the path name of a directory without a trailing All blanks are ignored when parsing this string It strips any trailing no list from the file name in the INCLUDE statement a Logical names in a file name are delimited by the first in the VMS file name so 77 converts file names of the name1 file form to the path1 file form a For logical names uppercase and lowercase are significant If a logical name is encountered on the INCLUDE statement which is not specified in the LOGICALNAMEMAPP ING the file name is used unchanged Examples Example 1 INCLUDE simple case INCLUDE stuff The above line is replaced by the contents of the file stuff Example 2 INCLUDE search paths 178 FORTRAN 77 Language Reference May 2000 For the following conditions Your source file has the line INCLUDE verl const h Your current working directory is usr ftn m Your source file is usr ftn projA myprg f In this example 77 seeks const h in these directories in the order shown For a standard install 77 searches these directories usr ftn projA verl usr ftn verl
240. ned by the generic function rules one is chosen that returns the prevailing length INTEGER 2 when the i2 compilation option is in effect With 1 2 the default length of LOGICAL quantities is 2 bytes Ordinary integers follow the FORTRAN rules about occupying the same space as a REAL variable They are assumed to be equivalent to the C type long int and 2 byte integers are of C type short int These short integer and logical quantities do not obey the standard rules for storage association An INTEGER 2 occupies 2 bytes byte boundaries GER 4 holds a signed integer INTEGER 2 is aligned on 2 INTEGER 4 The integer data type INTE An INTEGER 4 occupies 4 bytes INTEGER 4 is aligned on 4 byte boundaries GER 8 holds a signed 64 bit integer INTEGER 8 The integer data type INTE An INTEGER 8 occupies 8 bytes INTEGER 8 is aligned on 8 byte boundaries FORTRAN 77 Language Reference May 2000 28 LOGICAL The logical data type LOGICAL holds a logical value TRUE or FALSE The value 0 represents FALSE any other value represents TRUE The usual default size for an LOGICAL item with no size specified is 4 and is aligned on 4 byte boundaries However these defaults can be changed by compiling with certain special options LOGIC
241. next URE odeType 2 pr r pb b bbb ddd recet Num Initialize current record v Num malloc 12 pb Create next record Chapter 4 Statements END STRUC RECORD POINTER HARACTER v 3 4 aaa r next RETURN r recnum r label pb END demos 77 silent Linked f Linked f line 6 Warning local variable b never used Linked f line 31 Warning local variable b never used demo a out 1 aaa 2 bbb 3 Cee 4 ddd demo Remember Do not optimize programs using pointers like this with 03 04 or 05 The warnings can be ignored m This is not the normal usage of pointers described at the start of this section 216 FORTRAN 77 Language Reference May 2000 PRINT The PRINT statement writes from a list to stdout PRINT f iolist PRINT grname Parameter Description f Format identifier iolist List of variables substrings arrays and records grname Name of the namelist group Description The PRINT statement accepts the following arguments Format Identifier fis a format identifier and can be An asterisk which indicates list directed I O See List Directed I O on page 312 on for more information The label of a FORMAT statement that appears in the same program unit An integer variable name that has been assigned the label of a FORMAT statement t
242. ng rule is that if the first letter of the name is I J K L M or N then the data type is integer otherwise it is real 23 You can change the default implied types by using the IMPLICIT statement even to the extent of turning off all implicit typing with the IMPLICIT NONE statement You can also turn off all implicit typing by specifying the u compiler flag on the command line this is equivalent to beginning each program unit with the IMPLICIT NONE statement Array Elements An array element has the same type as the array name Functions Each intrinsic function has a specified type An intrinsic function does not require an explicit type statement but that is allowed A generic function does not have a predetermined type the type is determined by the type of the arguments as shown in Intrinsic Functions on page 325 An external function can have its type specified in any of the following ways a Explicitly by putting its name in a type statement Explicitly in its FUNCTION statement by preceding the word FUNCTION with the name of a data type Implicitly by its name as with variables Example Explicitly by putting its name in a type statement FUNCTION F INTEGER F X F X 1 RETUR END Example Explicitly in its FUNCTION statement EGER FUNCTION F X ER X 1 Q ETUR 134 ll x 24 FORTRAN 77 Language Reference May
243. ns 340 x VMS Intrinsic Functions 344 ASCII Character Set 351 Contents Sample Statements 355 Data Representations 365 Real Double and Quadruple Precision 365 Extreme Exponents 366 IEEE Representation of Selected Numbers 367 Arithmetic Operations on Extreme Values 367 Bits and Bytes by Architecture 369 VMS Language Extensions 371 Background 371 VMS Language Features in Sun Fortran 1 VMS Features Requiring x1 or vax spec 5 Index 381 FORTRAN 77 Language Reference May 2000 x Tables Special Character Usage 13 Items with Symbolic Names 4 Sample Symbolic Names 5 FORTRAN Statements 17 Default Data Sizes and Alignments in Bytes 31 Data Defaults Changed by i2 r8 dbl 32 Backslash Escape Sequences 36 Arithmetic Operators 70 Arithmetic Expressions 1 Arithmetic Operator Precedence 71 Logical Operators 0 Logical Operator Precedence 80 Operator Precedence 80 Logical Expressions and Their Meanings 81 Relational Operators 2 INQUIRE Statement Specifiers 181 Intrinsics That Cannot Be Passed As Actual Arguments 190 OPEN Statement Specifiers 198 OPTIONS Statement Qualifiers 5 xi TABLE 1 1 TABLE 1 2 TABLE 1 3 TABLE 1 4 TABLE 2 1 TABLE 2 2 TABLE 2 3 TABLE 3 1 TABLE 3 2 TABLE 3 3 TABLE 3 4 TABLE 3 5 TABLE 3 6 TABLE 3 7 TABLE 3 8 TABLE 4 1 TABLE 4 2 TABLE 4 3 TABLE 4 4 TABLE 5 1 Summary of 77 Input and Output 265 TABLE 5 2 Format Specifiers 5
244. nsfer Chapter4 Statements 223 If the input list is not empty data is transferred from the file to the corresponding items in the list The items are processed in order as long as the input list is not exhausted The next specified item is determined and the value read is transmitted to it Data editing in formatted READ is done according to the specified format In the third and fourth forms of namelist directed READ the items of the specified namelist group are processed according to the rules of namelist directed input The file is repositioned appropriately after data transfer If ios is specified and no error occurred it is set to zero ios is set to a positive value if an error or end of file was encountered If s is specified and end of file was encountered control is transferred to s If s is specified and an error occurs control is transferred to s There are two forms of READ READ f iolist READ grname The above two forms operate the same way as the others except that reading from the keyboard is implied Execution has the following differences When the input list is exhausted the cursor is moved to the start of the line following the input For an empty input list the cursor is moved to the start of the line following the input If an end of line CR or NL is reached before the input list is satisfied input continues from the next line
245. nvalid digit For hexadecimals enclose a string of hex digits in apostrophes and append the letter X FORTRAN 77 Language Reference May 2000 44 Example Hex alternate notation for typeless constants ab X BL iE VX 1f X 1fX Invalid missing trailing apostrophe ge Not numeric missing X 3g7 X Invalid invalid digit g Here are the rules and restrictions for binary octal and hexadecimal constants These constants are for use anywhere numeric constants are allowed These constants are typeless They are stored in the variables without any conversion to match the type of the variable but they are stored in the appropriate part of the receiving field low end high end If the receiving data type has more digits than are specified in the constant zeros are filled on the left If the receiving data type has fewer digits than are specified in the constant digits are truncated on the left If nonzero digits are lost an error message is displayed Specified leading zeros are ignored You can specify up to 8 bytes of data for any one constant at least that s all that are used If a typeless constant is an actual argument it has no data type but it is always 4 bytes that are passed For binary constants each digit must be 0 or 1 For octal constants each digit must be in the range 0 to 7 For hexadecimal constants each digit must be in the range 0 to 9 or in the range
246. o blanks followed by the number LOGICAL 2 L3 LOGICAL 4 L3 LOGICAL 8 L3 REAL 1PE14 5E2 REAL 8 122 L34 E2 REAL 16 1PE44 34E4 COMP LEX 32 and REAL 16 are SPARC only Unquoted Strings 77 list directed I O allows reading of a string not enclosed in quotes 314 FORTRAN 77 Language Reference May 2000 The string must not start with a digit and cannot contain separators commas or slashes or whitespace spaces or tabs A newline terminates the string unless escaped with a backslash Any string not meeting the above restrictions must be enclosed in single or double quotes Example List directed input of unquoted strings HARACTER C 6 8 READ I C 8 PRINT I C N 8 END Q The above program unquoted f reads and displays as follows demo a out 23 label 82 locked 23label 82locked demo Internal I O 77 extends list directed I O to allow internal I O 5 During internal list directed reads characters are consumed until the input list is satisfied or the end of file is reached During internal list directed writes records are filled until the output list is satisfied The length of an internal array element should be at least 20 characters to avoid logical record overflow when writing double precision values Internal list directed read was implemented to make command line decoding easier Internal list directed output should be avoide
247. o the specified unit then these variables are not returned ACCESS BLANK DIRECT FORM FORMATTED NAME NAMED NEXTREC NUMBER RECL SEQUENTIAL and UNFORMATTED If ACCESS SEQUENTIAL then these variables are not returned RECL and NEXTREC m If FORM UNFORMATTED then BLANK is not returned INQUIRE Specifier Keywords The following provides a detailed list of the INQUIRE specifier keywords ACCESS acc m acc is a character variable that is assigned the value SEQUENTIAL if the connection is for sequential I O and DIRECT if the connection is for direct I O The value is undefined if there is no connection BLANK bInk m blink is a character variable that is assigned the value NULL if null blank control is in effect for the file connected for formatted I O and ZERO if blanks are being converted to zeros and the file is connected for formatted I O DIRECT dir a dir is a character variable that is assigned the value YES if the file could be connected for direct I O NO if the file could not be connected for direct I O and UNKNOWN if the system can t tell ERR s sis a statement label of a statement to branch to if an error occurs during the execution of the INQUIRE statement 182 FORTRAN 77 Language Reference May 2000
248. ocates an area of memory and returns the address of the start of that area The argument to the function is an integer specifying the amount of memory to be allocated in bytes If successful it returns a pointer to the first item of the region otherwise it returns an integer 0 The region of memory is not initialized in any way Chapter 2 Data Types and Data Items 65 Example Memory allocation for pointers by MALLOC COMPLEX 2 REAL POINTER Pl P2 Y P3 Z Pl MALLOC 10000 In the above example MALLOC allocates 10 000 bytes of memory and associates the address of that block of memory with the pointer P1 Deallocation of Memory by FREE Subroutine The subroutine FREE deallocates a region of memory previously allocated by MALLOC The argument given to FREE must be a pointer previously returned by MALLOC but not already given to FREE The memory is returned to the memory manager making it unavailable to the programmer Example Deallocate via FREE POINTER Pl P2 Y P3 Z Pl MALLOC 10000 CALL FREE P1 In the above example MALLOC allocates 10 000 bytes of memory which are associated with pointer P1 FREE later returns those same 10 000 bytes to the memory manager Special Considerations Here are some special considerations when working with pointers and memo
249. of an E 42 FORTRAN 77 Language Reference May 2000 The restrictions are Other than the optional plus or minus sign a decimal point the digits 0 through 9 a blank and the letter Q No other characters are allowed The magnitude of an IEEE normalized quadruple precision floating point value must be in the approximate range 3 362Q 4932 1 20Q 4932 m It occupies 16 bytes of storage m Each such datum is aligned on 8 byte boundaries Typeless Constants Binary Octal Hexadecimal Typeless numeric constants are so named because their expressions assume data types based on how they are used 5 These constants are not converted before use However in 177 they must be distinguished from character strings The general form is to enclose a string of appropriate digits in apostrophes and prefix it with the letter B O X or Z The B is for binary the O is for octal and the X or Z are for hexadecimal Example Binary octal and hexadecimal constants DATA and PARAMETER PARAMETER Pl Z 1F INTEGER 2 1 N2 N3 4 DATA N1 B 0011111 1 3 2 0 37 N4 Z 1 WRITE 1 N1 N2 N3 N4 1 1 FORMAT 1X O4 O4 Z4 Z4 Z4 END Note the edit descriptors in FORMAT statements O for octal and Z for hexadecimal Each of the above integer constants has the value 31 decimal Example Binary octal and hexadecimal other than in DATA and PARAMETER
250. of type INTEGER then the number of characters that can be assigned is 2 or 4 for INTEGER 2 and INTEGER 4 respectively If the character constant or the Hollerith constant has fewer characters than the capacity of the item the constant is extended on the right with spaces If the character or the Hollerith constant contains more characters than can be stored the constant is truncated on the right Implied Do Lists An nlist can specify an implied DO list for initialization of array elements The form of an implied Do list is dlist iv m1 m2 m3 Parameter Description dlist List of array element names and implied Do lists iv Integer variable called the implied DO variable m1 Integer constant expression specifying the initial value of iv m2 Integer constant expression specifying the limit value of iv m3 Integer constant expression specifying the increment value of iv If m3 is omitted then a default value of 1 is assumed The range of an implied DO loop is dlist The iteration count for the implied DO is computed from m1 m2 and m3 and it must be positive Implied DO lists may also appear within the variables lists on I O statements PRINT READ and WRITE Chapter 4 Statements 119 Variables Variables can also be initialized in type statements This is an extension of the FORTRAN 77 Standard Examples are given under each of the individual type statements and under the general
251. ogical IF statement evaluates a logical expression and executes the specified statement if the value of the logical expression is true The specified statement is not executed if the value of the logical expression is false and execution continues as though a CONTINUE statement had been executed st can be any executable statement except a DO block IF ELSE IF ELSE END IF END or another logical IF statement Example IF VALUE LE ATAD CALL PUNT Note that there is no THEN IF TALLY GE 1000 RETURN Chapter4 Statements 173 IMPLICIT The IMPLICIT statement confirms or changes the default type of names IMPLICIT type a a type a 4 IMPLICIT NONE IMPLICIT UNDEFINED A Z u Parameter Description type BYTE u CHARACTER CHARACTER n where n must be greater than 0 CHARACTER COMPLEX COMPLEX 8 u COMPLEX 16 u COMPLEX 32 u SPARC only DOUBLE COMPLEX u DOUBLE PRECISION INTEGER INTEGER 2 INTEGER 4 u INTEGER 8 u LOGICAL LOGICAL 1 u LOGICAL 2 u LOGICAL 4 u LOGICAL 8 u REAL REAL 4 u REAL 8 u REAL 16 u SPARC only AUTOMATIC u STATIC u a Either a single letter or a range of single letters in alphabetical order A range of letters can be specified by the first and last letters of the range separated by a minus sign Description The different uses for implicit typing and no
252. ogram can appear in the executable program The same labeled common block cannot be specified in more than one block data subprogram in the same executable program The optional parameter name must not be the same as the name of an external procedure main program common block or other block data subprogram in the same executable program The name must not be the same as any local name in the subprogram Example BLOCK DATA INIT COMMON RANGE X0 1 DATA X0 X1 2 0 6 0 END Chapter4 Statements 101 The BYTE statement specifies the type to be 1 byte integer It optionally specifies array dimensions and initializes with values BYTE 6 Parameter Description v Name of a symbolic constant variable array array declarator function or dummy function 6 List of constants for the immediately preceding name Description This is a synonym for LOGICAL 1 A BYTE type item can hold the logical values TRUE FALSE one eight bit data item or an integer between 128 and 127 Example BYTE BIT3 8 01 M 127 SWITCH FALSE 102 FORTRAN 77 Language Reference May 2000 CALL The CALL statement branches to the specified subroutine executes the subroutine and returns to the calling program after finishing the subroutine CALL sub ar ar Parameter Description sub Name of the subroutine to be called ar Actua
253. omputing 6 Sun WorkShop 6 Compilers Fortran 77 95 Related Sun WorkShop 6 Documentation by Document Collection Continued Description Discusses issues relating to input output libraries program analysis debugging and performance Provides information on command line options and how to use the compilers Provides a complete language reference Describes the intrinsic INTERVAL data type supported by the Fortran 95 compiler Describes how to use the Sun WorkShop TeamWare code management tools Describes how to use Visual to create C and Java graphical user interfaces Discusses the optimized library of subroutines and functions used to perform computational linear algebra and fast Fourier transforms Describes how to use the Sun specific features of the Sun Performance Library which is a collection of subroutines and functions used to solve linear algebra problems Describes issues regarding the numerical accuracy of floating point computations Provides details on the Standard C Library Describes how to use the Standard C Library Provides details on the Tools h class library Discusses use of the C classes for enhancing the efficiency of your programs Document Title Fortran Programming Guide Fortran User s Guide FORTRAN 77 Language Reference Interval Arithmetic Programming Reference Sun WorkShop TeamWare 6 User s Guide Sun WorkShop Visual U
254. on page 31 325 CHAPTER 6 Arithmetic and Mathematical Functions This section details arithmetic type conversion trigonometric and other functions a stands for a function s single argument al and a2 for the first and second wa arguments of a two argument function and ar and ai for the real and imaginary parts of a function s complex argument EX 32 are SPARC only EAL 16 and COMPLI FORTRAN 77 Language Reference May 2000 Note that RI 326 327 EGER oO INTEGER INTEGER INTEGER NTEGER Function Type zZ DUUDDUDH D BL 1 O gt lt e e Intrinsic Functions DOUBLE COMPLEX DOUBLE COMPLEX COMPLEX 32 Argument Type Chapter 6 Specific Names IABS ABS DABS CABS QABS ZABS CDABS CQABS AINT DINT QINT ANINT DNINT QNINT NINT IDNINT IQNINT MOD AMO DMO QMO OU Cd ISIGN SIGN DSIGN QSIGN DI IM DI DIM PROD PROD eee a H O AX1 AX1 AX1 Arithmetic Functions No of Args Generic Name 1 ABS 1 AINT 1 ANINT 1 NINT 2 MOD 2 SIGN 2 DIM 2 22 MAX Arithmetic TABLE 6 1 Intrinsic Function Definition Absolute value lal See Note 6 ar ai2 2 Truncation int a int a 5
255. onstant can be a Hollerith constant or a string of characters delimited by apostrophes or quotes The character string cannot include the control characters Control A Control B or Control C that is you cannot hold down the Control key and press the A B or C keys If you need those control characters use the char function FORTRAN 77 Language Reference May 2000 92 If you use quotes to delimit a character constant then you cannot compile with the x1 option because in that case a quote introduces an octal constant The characters are transferred to the variables without any conversion of data and may not be portable Character expressions which include the operator can be assigned only to items of type CHARACTER Here the v is the name of a variable substring array element or record field of type CHARACTER e is a character expression Execution of a character assignment statement causes evaluation of the character expression and assignment of the resulting value to v If the length of e is more than that of v characters on the right are truncated If the length of e is less than that of v blank characters are padded on the right Record Assignment v and e are each a record or record field The e and v must have the same structure They have the same structure if any of the following occur a Both e and v are fields with the same elementary data type m Both e and v are re
256. opens a file for direct access formatted I O with a record length of 20 characters then reads the thirteenth record and converts it according to the I10 F10 3 format Chapter5 Input and Output 1 Internal Files An internal file is a character string object such as a constant variable substring array element of an array or field of a structured record all of type character For a variable or substring there is only a single record in the file but for an array each array element is a record Sequential Formatted I O On internal files the FORTRAN Standard includes only sequential formatted I O I O is not a precise term to use here but internal files are dealt with using READ and WRITE statements Internal files are used by giving the name of the character object in place of the unit number The first read from a sequential access internal file always starts at the beginning of the internal file similarly for a write Example Sequential formatted reads CHARACTER X 80 READ 5 A READ 13 14 Nl N2 The above code reads a print line image into X and then reads two integers from X Direct Access I O 77 extends direct I O to internal files This is like direct I O on external files except that the number of records in the file cannot be changed In this case a record is a single element of an array of character s
257. ormat specifier 278 boundary for variable alignment 31 Ww bounds on arrays 49 BYTE 102 byte and bit order 369 BYTE data type 25 BZ format specifier 278 anonymous field 58 245 ANSI X3 9 1978 FORTRAN standard 11 apostrophe character constants 34 36 direct access record 221 271 374 ELIST 316 format specifier 277 append on open 199 arguments dummy disallowed in NAMI fields 58 230 omitted 372 records 58 230 arithmetic assignment 74 assignment statement 94 expression 70 71 IF 169 intrinsic functions 327 operations on extreme values 367 operator 70 array adjustable bounds 50 assumed size 50 bounds 49 character 49 108 complex numbers 116 declarators 48 definition 48 dimensions 49 double complex 135 elements data types 24 disallowed in NAMELIST 316 input by NAMELIST 321 names with no subscripts 51 ordering 53 real 229 subscripts 51 ASCII character set 351 ASSIGN 89 assignment arithmetic 74 94 character 77 78 logical 81 statement 91 assumed size array 50 382 FORTRAN 77 Language Reference May 2000 substring operator 54 column one formatting 266 combinations of I O 265 commands 1 commas in formatted input 300 comments 19 1 19 19 blank line 19 C 19 embedded 372 end of line 19 372 COMMON 14 112 372 complex array 116 constant in NAMELIST 321 constants 3
258. ot in force Refer to the Fortran User s Guide for details of specific compiler options The following table summarizes the default size and alignment ignoring other aspects of types and options TABLE 2 1 Default Data Sizes and Alignments in Bytes Default Alignment Alignment in COMMON Fortran 77 Data Type Size SPARC x86 SPARC x86 BYTE X 1 CHARACTER X 1 CHARACTER n n 8 PPR COMPLEX X COMPLEX 8 X 8 DOUBLE COMPLEX X COMPLEX 16 COMPLEX 32 X Orr NDAD PPP PPP DOUBLE PRECISION X REAL X REAL 4 X REAL 8 X REAL 16 X A AAA a ORNE BR ORANA 2 OBB OO INTEGER X INTEGER 2 X INTEGER 4 X INTEGER 8 x LOGICAL X LOGICAL 1 LOGICAL 2 LOGICAL 4 LOGICAL 8 CORNER ORANA DORR DO DOOR erem PARNER PARANA ARABRA BRB BRA PP NP PEN PEN PB AANA xx xX Chapter 2 Data Types and Data Items 31 Note the following REAL 16 and COMPLEX 32 are only available on SPARC only In 64 bit environments compiling with xarch v9 v9a the default alignment is on 16 byte rather than 8 byte boundaries as indicated by 8 16 in the table m Arrays and structures align according to their elements or fields An array aligns the same as the array element A structure aligns the same as the field with the widest alignment Compiling with options i2 r8 or db1 changes the defaults for certain data declarations that appear without an explicit size r8 dbl
259. ou must use x1 d to access the following features Unformatted record size in words rather than bytes 81 VMS style logical file names 1 Quote character introducing octal constants x1 Backslash as ordinary character within character constants x1 Nonstandard form of the PARAMETER statement x1 H Appendix D VMS Language Extensions 375 Debugging lines as comment lines or FORTRAN statements x1d Align structures as in VMS FORTRAN x1 Details of Features That Require x1 d Here are the details Unformatted record size in words rather than bytes In 77 direct access unformatted files are always opened with the logical record size in bytes If the x1 d option is not set then the argument n in the OPEN option RECL n is assumed to be the number of bytes to use for the record size If the x1 d option is set then the argument n in the OPEN option RECL n is assumed to be the number of words so the compiler uses n 4 as the number of bytes for the record size If the x1 d option is set and if the compiler cannot determine if the file is formatted or unformatted then it issues a warning message that the record size may need to be adjusted This result could happen if the information is passed in variable character strings The record size returned by an INQUIRE statement is not adjusted by the compiler that is INQUIRE always returns the number o
260. p DISPOSI m DIS The a Special Intrinsics The compiler processes certain special intrinsic functions a VAL is accepted m 5100 is treated as LOC FORTRAN 77 Language Reference May 2000 374 oe REF expr is treated as expr with a warning if expris CHARACTER oe DESCR is reported as an untranslatable feature m Variable Expressions in FORMAT Statements In general inside a FORMAT statement any integer constant can be replaced by an arbitrary expression the single exception is the n in an nH edit descriptor The expression itself must be enclosed in angle brackets Example The 6 in the following statement is a constant 1 FORMAT 3F6 1 6 can be replaced by the variable N as in 1 FORMAT 3F lt N gt 1 VMS Features Requiring x1 or vax spec You get most VMS features automatically without any special options For a few of them however you must add the 1 option on the 77 command line In general you need this x1 option if a source statement can be interpreted for either a VMS way of behavior or an 77 way of behavior and you want the VMS way of behavior The x1 option forces the compiler to interpret it as VMS FORTRAN Note also the vax spec option which allows specification of these VMS extensions individually See the Fortran User s Guide for details Summary of Features That Require x1 d Y
261. parallelization Sun FORTRAN 77 accepts many VMS extensions so that programs originally written for VAX systems will port easily to Solaris Features implemented in Sun 77 that are not part of the applicable standards mentioned in Standards Conformance on page 11 are flagged with the special character mark throughout this manual Basic Terms Some of the FORTRAN basic terms and concepts are a A program consists of one or more program units A program unit is a sequence of statements terminated by an END A statement consists of zero or more key words symbolic names literal constants statement labels operators and special characters Each key word symbolic name literal constant and operator consists of one or more characters from the FORTRAN character set m A character constant can include any valid ASCII character A statement label consists of 1 to 5 digits with at least one nonzero Character Set The character set consists of the following Uppercase and lowercase letters A Z and a z Numerals 0 9 FORTRAN 77 Language Reference May 2000 12 Special characters The following table shows the special characters that are used for punctuation TABLE 1 1 Special Character Usage Character Name Usage Space Space Ignored in statements except as part of a character constant Tab Tab Establish the line as a tab format source line Equals Assignment Plu
262. part of Sun WorkShop FORTRAN 77 For information about Fortran library routines see the Fortran Library Reference Intrinsic functions that are Sun extensions of the ANSI FORTRAN 77 standard are marked with Intrinsic functions have generic and specific names when they accept arguments of more than one data type In general the generic name returns a value with the same data type as its argument However there are exceptions such as the type conversion functions TABLE 6 2 and the inquiry functions TABLE 6 7 The function may also be called by one of its specific names to handle a specific argument data type With functions that work on more than one data item e g sign al a2 all the data arguments must be the same type In the following tables the FORTRAN 77 intrinsic functions are listed by Intrinsic Function description of what the function does Definition a mathematical definition No of Args number of arguments the function accepts Generic Name the function s generic name Specific Names the function s specific names Argument Type data type associated with each specific name Function Type data type returned for specific argument data type Note Compiler options db1 12 r8 and xt ypemap change the default sizes of variables and have an effect on intrinsic references See Remarks on page 338 and the discussion of default sizes and alignment in Size and Alignment of Data Types
263. passed as 4 bytes unless compiled with the i2 option in which case it is passed as 2 Real Constants A real constant is an approximation of a real number It can be positive negative or zero It has a decimal point or an exponent If no sign is present the constant is assumed to be nonnegative Chapter 2 Data Types and Data Items 9 Real constants REAL 4 use 4 bytes of storage Basic Real Constant A basic real constant consists of an optional plus or minus sign followed by an integer part followed by a decimal point followed by a fractional part The integer part and the fractional part are each strings of digits and you can omit either of these parts but not both Example Basic real constants 82 2 90 98 5 Real Exponent A real exponent consists of the letter E followed by an optional plus or minus sign followed by an integer Example Real exponents Real Constant A real constant has one of these forms Basic real constant Basic real constant followed by a real exponent Integer constant followed by a real exponent A real exponent denotes a power of ten The value of a real constant is the product of that power of ten and the constant that precedes the E FORTRAN 77 Language Reference May 2000 40 Example Real constants 32 32 618 1 6E 7E3 1 6E12 1 0E2 0 Invalid not allowed error message
264. pe of v Type of e INTEGER 2 INTEGER 4 or INTEGER 8 INT e REAL REAL e REAL 8 REAL 8 REAL 16 SPARC only QREAL e SPARC only DOUBLE PRECISION DBLE e COMP LEX 8 CMPLX e COMPLEX 1 6 DCMPLX e COMPLEX 32 SPARC only QCMPLX e SPARC only Chapter4 Statements 1 Note Compiling with any of the options 12 db1 28 or xt ypemap can alter the default data size of variables and expressions This is discussed in Chapter 2 See also the Fortran User s Guide for a description of these options Example An assignment statement REAL A B DOUBLE PRECISION V VSR The above code is compiled exactly as if it were the following REAL A B DOUBLE PRECISION V V DBLE A B Logical Assignment v is the name of a variable array element or record field of type logical 6 is a logical expression or an integer between 128 and 127 or a single character constant Execution of a logical assignment statement causes evaluation of the logical expression 6 and assignment of the resulting value to v If e is a logical expression rather than an integer between 128 and 127 or a single character constant then e must have a value of either true or false Logical expressions of any size can be assigned to logical variables of any size The section on the LOGICAL statement provides more details on the size of logical variables Character Assignment The c
265. perators NODE GE 0 Kg Lil 7 Y UAV GT U V GT U V Mixed mode integer M N is promoted to real STRI LT STR2 STR1 and STR2 are character type S is character type FORTRAN 77 Language Reference May 2000 82 For character relational expressions Less than means precedes in the ASCII collating sequence If one operand is shorter than the other the shorter one is padded on the right with blanks to the length of the longer Constant Expressions A constant expression is made up of explicit constants and parameters and the FORTRAN operators Each operand is either itself another constant expression a constant a symbolic name of a constant or one of the intrinsic functions called with constant arguments Examples Constant expressions PARAMETER L 29002 P 3 14159 C along the PARAMETER I L 2 V 4 0 P 3 0 S C riverrun PARAMETER M MIN I L IA ICHAR A PARAMETER 0 6 406 D 2 3D9 0 66 VOLUME 10 3 20 3 1 1 There are a few restrictions on constant expressions Constant expressions are permitted wherever a constant is allowed except they are not allowed in DATA or standard FORMAT statements Constant expressions are permitted in variable format expressions Exponentiation to a floating point power is not allowed a warning is issued Chapter 3
266. ple _ _xfunc as this will conflict with the compiler s usage FORTRAN 77 Language Reference May 2000 14 Uppercase and lowercase are not significant the compiler converts them all to lowercase The U option on the 77 command line overrides this default thereby preserving any uppercase used in your source file 5 Example These names are equivalent with the default in effect m The space character is not significant Example These names are equivalent IF LT ATAD GO TO 9 IF LT A TAD GO TO 9 IF X LT ATAD GOTO9 Here are some sample symbolic names TABLE 1 3 Sample Symbolic Names Valid Invalid Reason X2 2X Starts with a digit DELTA_TEMP __DELTA_TEMP Starts with an _ _ reserved for the compiler YSDot Y Dot There is an invalid character In general for any single program unit different entities cannot have the same symbolic name The exceptions are A variable or array can have the same name as a common block a A field of a record can have the same name as a structure 9 a A field of a record can have the same name as a field at a different level of the structure Throughout any program of more than one programming unit no two of the following can have the same name Block data subprograms Common blocks Entry points Function subprograms Main program Subroutines Chapter 1 Elements of FORTRAN 5 Pro
267. ponding formal arguments and the body of the subroutine is executed 3 Normally the control is transferred back to the statement following the CALL statement upon executing a RETURN statement or an END statement in the subroutine If an alternate return in the form of RETURN n is executed then control is transferred to the statement specified by the n alternate return specifier in the CALL statement Note A CALL to a subprogram defined as a FUNCTION rather than as a SUBROUTINE will cause unexpected results and is not recommended The compiler does not automatically detect such inappropriate CALLs and no warning is issued unless the Xlist option is specified Examples Example 1 Character string HARACTER 25 TEXT EXT Some kind of text string ALL OOPS TEXT D UBROUTINE OOPS S CHARACTER S WRITE 03 S Sri 104 FORTRAN 77 Language Reference May 2000 Example 2 Alternate return CALL RANK 8 9 WRITE OK Normal Return STOP 8 WRITE Minor 1st alternate return STOP 9 WRITE Major 2nd alternate return STOP END SUBROUTINE RANK IF EQ 0 RETURN IF EQ 1 RETURN 1 RETURN 2 Example 3 Another form of alternate return the amp is nonstandard CALL RANK amp 8 amp 9 Example 4 Array array element and variable
268. ption handler amounts to recursive I O See the next paragraph m Recursive I O does not work reliably If you list a function in an I O list and if that function does I O then during runtime the execution may freeze or some other unpredictable problem results This risk exists independent of using parallelization Example Recursive I O fails intermittently WRITE x f x Not allowed because f does I O UNCTION F X RITE X ETURN Comments If u specifies an external unit that is not connected to a file an implicit OPEN operation is performed that is equivalent to opening the file with the following options OPEN u FILE FORT u STATUS UNKNOWN amp ACCESS SEQUENTIAL FORM fmt The value of fmt is FORMATTED if the write is formatted and UNFORMATTED otherwise FORTRAN 77 Language Reference May 2000 260 201 A simple unsubscripted array name specifies all of the elements of the array in memory storage order with the leftmost subscript increasing more rapidly The record number for direct access files starts from one onwards Namelist directed output is permitted on sequential access files only Examples Example 1 Formatted write with trap I O errors and I O status WRITE 1 2 ERR 8 IOSTAT N X Y RETURN 8 WRITE I O error on T STOP END
269. r 348 intrinsic 327 length specifier 373 malloc 65 memory allocation and deallocation 338 names 14 type coercing 349 types 24 zero extend 350 G G format specifier 299 general real editing 299 GO TO 164 168 GO TO assigned 164 GO TO unconditional 168 GO TO computed 166 H hex and octal format 287 format samples 288 input 287 input rules 288 output 288 289 hexadecimal constants 43 initialization 43 hollerith 94 284 horizontal positioning 289 l I format specifier 284 I O 265 allowable combinations 265 binary 310 direct 270 errors 264 random 270 L L format specifier 286 label of statement 12 leading spaces or zeros hex and octal output 289 left to right exception 71 precedence 71 len declared length 109 length function length specifier 161 163 373 LEN function 109 line of source code 18 names 14 string 109 variable length records 200 line formats 17 length 18 tab format 17 372 line feed 77 linked list 215 list directed I O 312 input 312 output 312 output to a print file 267 literal constant 12 literals type REAL 16 373 loc 65 338 location of scratch files 201 LOGICAL 29 191 logical assignment 81 94 constants 39 editing 286 expression 80 expression meaning 81 file names in the INCLUDE 178 file names VMS 375 376 IF 173 integer mixed 74 LOGICAL 1 data type 25 operator precedence
270. r Precedence Operator Precedence NOT Highest AND NEQV XOR EQV Lowest If the logical operators are of equal precedence they are evaluated left to right If the logical operators appear along with the various other operators in a logical expression the precedence is as follows TABLE 3 6 Operator Precedence Operator Precedence Arithmetic Highest Character Relational Logical Lowest FORTRAN 77 Language Reference May 2000 80 The following table shows the meanings of simple expressions TABLE 3 7 Logical Expressions and Their Meanings Expression Meaning are true and AND Y Both or Y or both are true Either NEQV Y X and Y are not both true and not both false or Y is true but not both Either XOR are both true or both false and NOT X Logical negation Logical operations on operands of different sizes result in a logical value promoted to the size of the largest operand For example L2 AND L4 gives a LOGICAL 4 result if L2 is LOGICAL 2 and L4 is LOGICAL 4 BYTE variables are treated the same as LOGICAL 1 Logical Assignment This is the syntax for the assignment of the value of a logical expression to a logical variable v e e A logical expression an integer between 128 and 127 or a single character constant v A logical variable array element or record field E
271. racter variable or character array element can contain characters equal in number to its length A character array can contain characters equal in number to the length of each element multiplied by the number of elements 5 The interaction between the format identifier and the I O list is the same as for a formatted I O statement Example A program using DECODE ENCODE CHARACTER 5 6 987654 T 6 INTEGER V 3 4 DECODE 6 312 S V W RITE 313 V 6005 6 312 T V 3 V 2 V 1 PRINT T END The above program has this output 98 76 54 547698 The DECODE reads the characters of S as 3 integers and stores them into V 1 V 2 and V 3 The ENCODE statement writes the values V 3 V 2 and V 1 into T as characters T then contains 547698 122 FORTRAN 77 Language Reference May 2000 DIMENSION The DIMENSION statement specifies the number of dimensions for an array including the number of elements in each dimension Optionally the DIMENSION statement initializes items with values DIMENSION a d a d Parameter Description a Name of an array d Specifies the dimensions of the array It is a list of 1 to 7 declarators separated by commas Description This section contains descriptions for the dimension declarator and the arrays Dimension D
272. rce lines are defined as follows A tab in any of columns 1 through 6 or an ampersand in column 1 establishes the line as a tab format source line If the tab is the first nonblank character the text following the tab is scanned as if it started in column 7 A comment indicator or a statement number can precede the tab Continuation lines are identified by an ampersand amp in column 1 or a nonzero digit after the first tab Mixing Formats You can format lines both ways in one program unit but not in the same line Continuation Lines The default maximum number of continuation lines is 99 1 initial and 99 continuation To change this number of lines use the N17 option Extended Lines To extend the source line length to 132 characters use the e option Otherwise by default 77 ignores any characters after column 72 Example Compile to allow extended lines demos 77 e prog f FORTRAN 77 Language Reference May 2000 18 Padding Padding is significant in lines such as the two in the following DATA statement C 1 2 3 4 5 6 7 C23456789012345678901234567890123456789012345678901234567890123456789012 DATA SIXTYH 60H 1 Comments and Blank Lines A line with a c C d D or in column one is 8 comment line except that if the x1d option is set then the lines starting with D or d are compiled as debug lines 19 The ad D and are nonstandard
273. rence May 2000 Example 2 Let the compiler count the characters FADING HEADING I O Error Number CHARAC PARAME Example 3 The alternate syntax if the 1 compilation flag is specified LOGICAL FLAG1 ER FLAG1 T PARAME An ambiguous statement that could be interpreted as either a PARAMETER statement or an assignment statement is always taken to be the former as long as either the x1 or x1d option is specified Example An ambiguous statement PARAMETER S TRUE With 1 the above statement is a PARAMETER statement about the variable S PARAMETER S TRUE It is not an assignment statement about the variable PARAMETERS ERS TRUE Chapter4 Statements 209 T PARAME PAUSE The PAUSE statement suspends execution and waits for you to type go PAUSE str Parameter Description str String of not more than 5 digits or a character constant Description The PAUSE statement suspends program execution temporarily and waits for acknowledgment On acknowledgment execution continues If the argument string is present it is displayed on the screen written to stdout followed by the following message PAUSE To resume execution type go Any other input will term
274. repeatedly executes a set of statements DO s loop control or DO loop control where s is a statement number The form of loop control is variable 61 e2 e3 Parameter Description variable Variable of type integer real or double precision el e2 Expressions of type integer real or double precision e3 specifying initial limit and increment values respectively Description The DO statement contains the following constructs Labeled DO Loop A labeled DO loop consists of the following m DO statement m Set of executable statements called a block Terminal statement usually a CONTINUE statement Terminal Statement The statement identified by s is called the terminal statement It must follow the DO statement in the sequence of statements within the same program unit as the DO statement The terminal statement should not be one of the following statements a Unconditional GO TO m Assigned GO TO a Arithmetic IF FORTRAN 77 Language Reference May 2000 126 Block IF ELSE IE SE D IF TURN OP D DO HF EENEN NE wW If the terminal statement is a logical IF statement it can contain any executable statement except DO DO WHILE Block IF ELSE IE SE IE SE DIF END Logical IF F F DO Loop Range The range of a DO loop consists of all of the executable statements that appear following the DO statement up to and
275. rever the compiler expects INTEGER explicitly it will not allow BYTE Chapter 2 Data Types and Data Items 5 Examples BYTE Bit3 8 01 W Counter 0 Switch FALSE A BYTE item occupies 1 byte 8 bits of storage and is aligned on 1 byte boundaries CHARACTER The character data type CHARACTER which has the synonym CHARACTER 1 holds one character The character is enclosed in apostrophes or quotes Allowing quotes is nonstandard if you compile with the x1 option quotes mean something else and you must use apostrophes to enclose a string The data of type CHARACTER is always unsigned A CHARACTER item occupies 1 byte 8 bits of storage and is aligned on 1 byte boundaries CHARACTER n The character string data type CHARACTER n where n gt 0 holds a string of n characters A CHARACTER n data type occupies n bytes of storage and is aligned on 1 byte boundaries Every character string constant is aligned on 2 byte boundaries If it does not appear in a DATA statement it is followed by a null character to ease communication with C routines COMPLEX A complex datum is an approximation of a complex number The complex data type COMPLEX which defaults to a synonym for COMPLEX 8 is a pair of REAL 4 values that represent a complex number The first element represents the real part and the s
276. risk This rule is nonstandard If a function appears in the output list that function must not cause an input output statement to be executed Namelist Directed WRITE The second form of WRITE is used to output the items of the specified namelist group Here grname is the name of the list previously defined in a NAMELIST statement Execution Execution proceeds as follows The file associated with the specified unit is determined The format if specified is established The file is positioned appropriately prior to data transfer If the output list is not empty data is transferred from the list to the file Data is edited according to the format if specified In the second form of namelist directed WRITE the data is transferred from the items of the specified namelist group according to the rules of namelist directed output The file is repositioned appropriately after the data transfer Chapter4 Statements 259 5 If ios is specified and no error occurs it is set to zero otherwise it is set to a positive value If s is specified and an error occurs control is transferred to s Restrictions Note these restrictions Output from an exception handler is unpredictable If you make your own exception handler do not do any FORTRAN output from it If you must do some then call abort right after the output Doing so reduces the relative risk of a system freeze FORTRAN I O from an exce
277. ro digits the field is zero filled on the left to a total of m digits m has no effect on input Octal and Hex Input A READ with the 0 or Z field descriptors in the FORMAT reads in w characters as octal or hexadecimal respectively and assigns the value to the corresponding member of the I O list Example Octal input the external data field is 654321 The first digit in the example appears in input column 1 The program that does the input is READ 2 2 FORMAT 06 Chapter5 Input and Output 287 The above data and program result in the octal value 654321 being loaded into the variable M Further examples are included in the following table TABLE 5 6 Sample Octal Hex Input Values Format External Field Internal Octal or Hex Value 04 1234A 1234 04 16234 1623 03 97AAA Error 9 not allowed 5 A23DEA A23DE 5 A23DEF A23DE won 24 95 2 Error not allowed The general rules for octal and hex input are For octal values the external field can contain only numerals 0 through 7 For hexadecimal values the external field can contain only numerals 0 through 9 and the letters A through F or a through f m Signs decimal points and exponent fields are not allowed All blank fields are treated as having a value of zero Ifa data item is too big for the corresponding variable an error message is displayed Octal and Hex Output A WRITE
278. roup Description ACCEPT f iolist is equivalent to READ f iolist and is for compatibility with older versions of FORTRAN An example of list directed input 1 VECTOR 10 EPT NODE V 88 FORTRAN 77 Language Reference May 2000 ASSIGN The ASSIGN statement assigns a statement label to a variable ASSIGN s TO i Parameter Description 5 Statement label i Integer variable Description The label s is the label of an executable statement or a FORMAT statement The statement label must be the label of a statement that is defined in the same program unit as the ASSIGN statement The integer variable i once assigned a statement label can be reassigned the same statement label a different label or an integer It can not be declared INTEGER 2 After assigning a statement label to a variable you can reference it in An assigned GO TO statement An input output statement as a format identifier Restrictions The variable must be assigned a statement label before referencing it as a label in an assigned GO TO statement or as a format identifier While i is assigned a statement label value do no arithmetic with i On 64 bit platforms the actual value stored in variable i by the ASSIGN statement is not available to the program except by the assigned GO TO statement or as a format identifier in an I O statement Also only variables set by an ASSIGN statemen
279. rrides the d value The specified input output list item must be of type real On input the specified list item becomes defined with a real datum On output the specified list item must be defined as a real datum The output field for the Fw d edit specifier has the width w The value is right justified in that field The field consists of zero or more leading blanks followed by either a minus if the value is negative or an optional plus followed by the magnitude of the value of the list item rounded to d decimal digits w must allow for a minus sign at least one digit to the left of the decimal point the decimal point and d digits to the right of the decimal point Therefore it must be the case that w d 3 Example Real input with F editing in the program Finp f CHARACTER LINE 24 12345678 23 5678 345678 READ LINE F8 3 F8 3 F8 3 R S T PRINT E 903 947 96 Jp OR Sy T END The program displays 12345 678DD23 5678D0 345678 298 FORTRAN 77 Language Reference May 2000 In the above example the first input data item has no decimal point so F8 3 determines the decimal point The other input data items have decimal points so those decimal points override the F edit descriptor as far as decimal points are concerned Example Real output with F editing in the program Fout f R 1234 678 PRINT 1 R R 1 FORMAT F9 3 F8 4 F
280. ry allocation with malloc loc and free The pointers are of type integer and are automatically typed that way by the compiler You must not type them yourself a A pointer based variable cannot itself be a pointer The pointer based variables can be of any type including structures 66 FORTRAN 77 Language Reference May 2000 No storage is allocated when such a pointer based variable is declared even if there is a size specification in the type statement You cannot use a pointer based variable as a dummy argument or in COMMON EQUIVALENCE DATA or NAMELIST statements The dimension expressions for pointer based variables must be constant expressions in main programs In subroutines and functions the same rules apply for pointer based array variables as for dummy arguments the expression can contain dummy arguments and variables in common Any variables in the expressions must be defined with an integer value at the time the subroutine or function is called Address expressions cannot exceed the range of INTEGER 4 on 32 bit environments If the expression is not in the range 2147483648 2147483647 then the results are unpredictable When compiling for 64 bit environments use malloc 64 to access the 64 bit address space Routine 8110064 takes an INTEGER 8 argument and returns a 64 bit pointer value In 64 bit programs pointers defined by
281. s See VMS Language Extensions on page 371 for details on other bitwise operations 14 Shift LSHIFT shifts a1 logically left by a2 bits inline code LRSHFT shifts a1 logically right by a2 bits inline code RSHIFT shifts a1 arithmetically right by a2 bits ISHFT shifts a1 logically left if a2 gt 0 and right if a2 lt 0 The LSHIFT and RSHIFT functions are the FORTRAN analogs of the C lt lt and gt gt operators As in C the semantics depend on the hardware The behavior of the shift functions with an out of range shift count is hardware dependent and generally unpredictable In this release shift counts larger than 31 result in hardware dependent behavior 15 Environmental inquiries Only the type of the argument is significant 16 Epsilon Epsilon is the least e such that 1 0 e 1 0 Chapter 6 Intrinsic Functions 343 LOC MALLOC and FREE LOC function returns the address of a variable or of an external procedure The 17 1 The function call MALLOC n allocates a block of at least n bytes and returns the address of that block LOC returns default INTEGER 4 in 32 bit environments INTEGER 8 in 64 bit environments MALLOC is a library function and not an intrinsic It too returns default INTEGER 4 bit environments INTEGER 8 in 64 bit environments However MALLOC must in 32 be explicitly declared IN
282. s 58 245 hex and octal output 289 NAMELIST 316 names 14 pointers 66 Q edit descriptor 302 records 58 230 structures 57 244 substructures 62 RETURN 233 return alternate 233 234 374 reverse solidus 13 REWIND 235 rshift 343 runtime formats 217 222 258 284 305 307 5 S edit descriptor 303 same line response 279 sample statements 355 SAVE 237 scale control 302 factor 302 scratch files defined 268 location 202 naming 201 SCRATCH option for OPEN 201 SEQUENTIAL option for ACCESS in OPEN file 199 Index 1 type REAL 16 literals 373 quadruple precision See quad quote 375 377 character constants 34 format specifier 293 preceding octal constants 39 R r4 32 radix 294 radix 50 constant 372 random I O 270 READ 221 read into hollerith edit descriptor 284 REAL 30 7 expressions illegal 373 intrinsic 329 real arrays 229 constants 39 data representation of reals 365 editing 294 298 EAL 16 30 42 373 EAL 4 30 40 EAL 8 30 41 ECL specifier in OPEN 200 ecl 1 variable length records 200 ECORD 230 record 56 argument that is a record 58 230 assignment 95 AUTOMATIC not allowed in 231 COMMON with a record 58 230 DATA not allowed in 58 231 DIMENSION witha record 58 disallowed in NAMELIST 316 EQUIVALENCE not allowed in 58 231 AMELIST not allowed in 58 231 PARAMETER not allowed in 231 reference 59 SAVE not allo
283. s If you put the calling the routines on different files you can optimize one and not optimize the other Example A relatively safe kind of coding with 03 1 REAL A B V 100 100 This programming unit does POINTER P V nothing else with P other than P MALLOC 10000 getting the address and passing it CALL CALC P A wa D UBROUTINE CALC ARRAY v mW ETURN END If you want to optimize only CALC at level 04 then avoid using pointers in CALC Some Problematic Code Practices Any of the following coding practices and many others could cause problems with an optimization level of 03 or 04 A program unit does arithmetic with the pointer A subprogram saves the address of any of its arguments between calls A function returns the address of any of its arguments although it can return the value of a pointer argument m A variable is referenced through a pointer but the address of the variable is not explicitly taken with the LOC or MALLOC functions Example Code that could cause trouble with 03 1 Possible problems here if optimized The compiler assumes that a reference through P may change A but not B this assumption could produce incorrect code FORTRAN 77 Language Reference May 2000 68 Expressions This chapter discusses Fortran expressions and how they are evaluated CHAPTER 3 Expr
284. s and can appear in more than one namelist Only the items specified in the namelist can be read or written in namelist directed I O but it is not necessary to specify data in the input record for every item of the namelist The order of the items in the namelist controls the order in which the values are written in namelist directed output The items in the input record can be in any order Chapter4 Statements 195 Restrictions Input data can assign values to the elements of arrays or to substrings of strings that ELTA appear in a namelist The following constructs cannot appear in a NAMELIST statement Constants parameters Array elements Records and record fields Character substrings Dummy assumed size arrays Example Example The NAMELIST statement HARACTER 16 SAMPLE OGICAL 4 NEW x4 DELTA ELIST CASE NEW and D In this example the group CASE has three variables SAMPLE FORTRAN 77 Language Reference May 2000 196 OPEN The OPEN statement can connect an existing external file to a unit create a file and connect it to a unit or change some specifiers of the connection OPEN UNIT u slist Parameter Description UNIT Unit number slist The specifiers list slist can include one or more of the following FILE fin or alternatively NAME fin ACCESS acc BLANK ERR 8
285. s 20 characters then changes columns 10 and 20 Example Input TRn and TL n relative tabs the program reads demo cat rtabi f CHARACTER C S T PEN 1 FILE mytab data O DO I 1 2 READ 1 2 C 5 1 2 FORMAT Al 795 Al TL4 Al PRINT C S T END DO END demo The two line data file is demo cat mytab data defguvwx 12345678 demo The run and the output are demo a out dwg 174 demo The above example reads column 1 then tabs right 5 to column 7 then tabs left 4 to column 4 292 FORTRAN 77 Language Reference May 2000 Example Output TR n and TL n relative tabs this program writes an output file demo cat rtabo f CHARACTER C 20 12345678901234567890 OPEN 1 FILE rtabo rep Ig Ze Jog ey eae 2 FORMAT A20 TL11 Al TRY Al END demo The run shows nothing but you can list the mytab rep output file demo cat rtabo rep 123456789 123456789 demo The above program writes 20 characters tabs left 11 to column 10 then tabs right 9 to column 20 Quotes Editing aaa The quotes edit specifier is in the form of a character constant It causes characters to be written from the enclosed characters of the edit specifier itself including blanks A quotes edit specifier must not be used on input The width of the field is the number of characters contained in but not includin
286. s Add unary operator Minus Subtract unary operator Asterisk Multiply alternate returns comments exponentiation stdin stdout list directed I O Slash Divide delimit data labeled commons structures end of record Parentheses Enclose expressions complex constants equivalence parameter or implicit groups formats argument lists subscripts Comma Separator for data expressions complex constants equivalence groups formats argument lists subscripts Period Radix point delimiter for logical constants and operators record fields Apostrophe Quoted character literals 4 Quote Quoted character literals octal constants Dollar sign Delimit namelist input edit descriptor directives Exclamation Comments Colon Array declarators substrings edit descriptor Percent Special functions REF VAL LOC amp Ampersand Continuation alternate return delimit namelist input use in column 1 establishes the line as a tab format source line Question Request names in namelist group mark Backslash Escape character lt gt Angle Enclose variable expressions in formats 9 brackets Note the following usage and restrictions Chapter 1 Elements of FORTRAN 13 Uppercase or lowercase is not significant in the key words of FORTRAN statements or in symbolic names The U option of 77 makes case significant in symbolic names Most control characters are allowed as data e
287. s an internal file that record is filled with blanks Direct Access Each slash increases the record number by one and the file is positioned at the start of the record with that record number On output two successive slashes produce a record of no characters and that record is filled with blanks Termination Control The colon edit descriptor allows for conditional termination of the format If the I O list is exhausted before the format then the format terminates at the colon FORTRAN 77 Language Reference May 2000 304 06011 5 The colon edit descriptor DATA INIT 3 LAST 8 WRITE 2 INIT WRITE 2 INIT LAST 2 PORMAT ENT TR Se 119 ag SX AST 7 225 END The above program produces output like the following Without the colon the output is more like this Example Termination control INIT INIT LAST INIT INIT LAST LAST Runtime Formats You can put the format specifier into an object that you can change during execution Doing so improves flexibility There is some increase in execution time because this kind of format specifier is parsed every time the I O statement is executed These are also called variable formats The object must be one of the following kinds Character expression The character expression can be a scalar an array an f a structured record the concatenation et its character v
288. s but only 4 byte arithmetic FORTRAN 77 Language Reference May 2000 32 There are two additional possibilities on SPARC xtypemap real 64 double 64 integer mixed xtypemap real 64 double 64 integer 64 which map both default REAL and DOUBLE to 8 bytes and should be preferable over using r8 1 Note that INTEGER and LOGICAL are treated the same and COMPLEX is mapped as two REAL values Also DOUBLE COMPLEX will be treated the way DOUBLE is mapped Options f or dalign SPARC only force alignment of all 8 16 or 32 byte data onto 8 byte boundaries Option db1_align_all1 causes all data to be aligned on 8 byte boundaries Programs that depend on the use of these options may not be portable See the Fortran User s Guide for details on these compiler options Constants A literal constant is a datum whose value cannot change throughout the program unit The form of the string representing a constant determines the value and data type of the constant For a named constant defined by a PARAMETER statement the name defines the data type There are three general kinds of constants a Arithmetic m Logical Character Blank characters within an arithmetic or logical constant do not affect the value of the constant Within character constants they do affect the value Here are the different ki
289. s treated as JCOUNT ICOUNT 451 If the x1 d option is not on then the 703 is an error With x1 d the VMS FORTRAN notation 703 signals 77 to convert from the integer octal constant to its integer decimal equivalent 451 in this case In VMS FORTRAN 703 cannot be the start of a character constant because VMS FORTRAN character constants are delimited by apostrophes not quotes m Backslash as ordinary character within character constants If the x1 d option is on a backslash in a character string is treated as an ordinary character otherwise it is treated as an escape character Nonstandard form of the PARAMETER statement The alternate PARAMETER statement syntax is allowed if the x1 d option is on Example VMS alternate form of PARAMETER statement omits the parentheses PARAMETER FLAG1 TRUE Debugging lines as comment lines or FORTRAN statements x1d The compiler interprets debugging lines as comment lines or FORTRAN statements depending on whether the x14 option is set If set they are compiled otherwise they are treated as comments Appendix VMS Language Extensions 377 Example Debugging lines ADS O gO 607s TOG 8 0p 90 With x1d this code prints I and X Without x1d it does not print them Align structures as in VMS FORTRAN Use this feature if your program has some de
290. s with the first executable statement after the ENTRY statement The ENTRY statement is a nonexecutable statement The entry name cannot be used in the executable statements that physically precede the appearance of the entry name in an ENTRY statement Argument Correspondence The formal arguments of an ENTRY statement need not be the same in order number ENTRY statements E and other type and name as those for FUNCTION SUBROUTINI in the same subprogram Each reference to a function subroutine or entry must use FORTRAN 77 Language Reference May 2000 150 an actual argument list that agrees in order number type and name with the dummy argument list in the corresponding FUNCTION SUBROUTINE or ENTRY statement Alternate return arguments in ENTRY statements can be specified by placing asterisks in the dummy argument list Ampersands are valid alternates ENTRY statements that specify alternate return arguments can be used only in subroutine subprograms not functions Restrictions An ENTRY statement cannot be used within a block IF construct or a DO loop If an ENTRY statement appears in a character function subprogram it must be defined as type CHARACTER with the same length as that of a function subprogram Examples Example 1 Multiple entry points in a subroutine UBROUTINE FIN A B C EGER A B CHARACTER C 4 H Ww RETUR
291. sS amp Sun microsystems FORTRAN 77 Language Reference Sun WorkShop 6 Sun Microsystems Inc 901 San Antonio Road Palo Alto CA 94303 U S A 650 960 1300 Part No 806 3594 10 May 2000 Revision A Send comments about this document to docfeedback sun com Copyright 2000 Sun Microsystems Inc 901 San Antonio Road Palo Alto CA 94303 4900 USA All rights reserved This product or document is distributed under licenses restricting its use copying distribution and decompilation No part of this product or document may be reproduced in any form by any means without prior written authorization of Sun and its licensors if any Third party software including font technology is copyrighted and licensed from Sun suppliers Parts of the product may be derived from Berkeley BSD systems licensed from the University of California UNIX is a registered trademark in the U S and other countries exclusively licensed through X Open Company Ltd For Netscape Netscape Navigator and the Netscape Communications Corporation logo the following notice applies Copyright 1995 Netscape Communications Corporation All rights reserved Sun Sun Microsystems the Sun logo docs sun com AnswerBookz2 Solaris SunOS JavaScript SunExpress Sun WorkShop Sun WorkShop Professional Sun Performance Library Sun Performance WorkShop Sun Visual WorkShop and Forte are trademarks registered trademarks or service marks of Sun Microsystems
292. script expression must be within the bounds for the appropriate dimension of the array A subscript of the form L1 Ln where each Li is the lower bound of the respective dimension references the first element of the array A subscript of the form U1 Un where each Ui is the upper bound of the respective dimension references the last element of the array Array element A n is not necessarily the n element of array A In the above example the fourth element of V is set to zero FORTRAN 77 Language Reference May 2000 52 Subscript expressions cannot exceed the range of INTEGER 4 in 32 bit environments It is not controlled but if the subscript expression is not in the range 2147483648 2147483647 then the results are unpredictable When compiled for 64 bit environments INTEGER 8 subscript expressions are allowed Array Ordering Array elements are usually considered as being arranged with the first subscript as the row number and the second subscript as the column number This corresponds to traditional mathematical nxm matrix notation 141 812 83 atm 421 22 42m aij aim an 1 an 2 an m Element a j is located in row i column j For example INTEGER 4 A 3 2 The elements of A are conceptually arranged in 3 rows and 2 columns A 1 1 A 1 2 A 2 1 A 2 2 A 3 1 A 3 2 Array elements are stored in column major order Example For the array A they are locate
293. ser s Guide Sun Performance Library Reference Sun Performance Library User s Guide Numerical Computation Guide Standard C Class Library Reference Standard C Library User s Guide Tools h Class Library Reference Tools h User s Guide TABLE P 3 Document Collection Forte TeamWare 6 Sun WorkShop TeamWare 6 Forte Developer 6 Sun WorkShop Visual 6 Forte Sun Performance Library 6 Numerical Computation Guide Standard Library 2 Tools h 7 FORTRAN 77 Language Reference May 2000 9 TABLE P 4 describes related Solaris documentation available through the Description Describes the operations of the Solaris link editor and runtime linker and the objects on which they operate Provides information for developers about the special built in programming tools that are available in the Solaris operating environment Preface docs sun com Web site TABLE 4 Related Solaris Documentation Document Collection Document Title Solaris Software Developer Linker and Libraries Guide Programming Utilities Guide 10 FORTRAN 77 Language Reference May 2000 CHAPTER 1 Elements of FORTRAN This chapter introduces the basic elements of Sun WorkShop FORTRAN 77 Standards Conformance 77 was designed to be compatible with the ANSI X3 9 1978 FORTRAN standard and the corresponding International Organization for Standardization ISO
294. specified in the nlist An array name if present refers to the first element of the array If an array element name appears in an EQUIVALENCE statement the number of subscripts can be less than or equal to the number of dimensions specified in the array declarator for the array name Restrictions In nlist dummy arguments and functions are not permitted Subscripts of array elements must be integer constants greater than the lower bound and less than or equal to the upper bound EQUIVALENCE can associate automatic variables only with other automatic variables or undefined storage classes These classes must be ones which are not in any of the COMMON STATIC SAVE DATA or dummy arguments An EQUIVALENCE statement can associate an element of type character with a noncharacter element 9 Chapter4 Statements 153 EQUIVALENCE statement cannot specify that the same storage unit is to occur An more than once in a storage sequence For example the following statement is not allowed EQUIVALENCE statement cannot specify that consecutive storage units are to be ENSION A UIVALENCE An nonconsecutive For example the following statement is not allowed ENCE statements are used together several D 2 D 1 EQUIVAL REAL A 2 DOUBLE PRECISION EQUIVALENCE A 1 When C
295. ssue a warning if the result overflows the INTEGER 4 data range To use INDEX in a 64 bit environment with character strings larger than the INTEGER 4 limit 2 Gbytes the INDEX function and the variables receiving the result must be declared INTEGER 8 11 LEN LEN returns the declared length of the CHARACTER argument variable The actual value of the argument is of no importance FORTRAN 77 Language Reference May 2000 342 LEN returns default INTEGER 4 data If compiling for a 64 bit environment the compiler will issue a warning if the result overflows the INTEGER 4 data range To use LEN in a 64 bit environment with character variables larger than the INTEGER 4 limit 2 Gbytes the LEN function and the variables receiving the result must be declared INTEGER 8 12 Lexical Compare 2 X Y is true if X Y or if X follows Y in the collating sequence otherwise it is false LGT X Y is true if follows Y in the collating sequence otherwise it is false LE X Y is true if X Y or if X precedes Y in the collating sequence otherwise t is false LT Y is true if X precedes Y in the collating sequence otherwise it is false If the operands for LGE LGT LLE and LLT are of unequal length the shorter operand is considered as if it were extended on the right with blanks 13 Bit Function
296. st Parameter Description cb Common block name nlist List of variable names array names and array declarators Description If the common block name is omitted then blank common block is assumed Any common block name including blank common can appear more than once in COMMON statements in the same program unit The list nlist following each successive appearance of the same common block name is treated as a continuation of the list for that common block name The size of a common block is the sum of the sizes of all the entities in the common block plus space for alignment Within a program all common blocks in different program units that have the same name must be of the same size However blank common blocks within a program are not required to be of the same size Restrictions Formal argument names and function names cannot appear in a COMMON statement An EQUIVALENCE statement must not cause the storage sequences of two different common blocks in the same program unit to be associated See Example 2 An EQUIVALENCE statement must not cause a common block to be extended on the left hand side See Example 4 FORTRAN 77 Language Reference May 2000 112 Examples Example 1 Unlabeled common and labeled common ENSION 100 DIM COMI ON LIMITS I J COM In the above example V and M are in the unlabeled common block I and J are named common block
297. st be an integer variable or an integer array element Record Number rn must be a positive integer expression and can be used for direct access files only rn can be specified for internal files FORTRAN 77 Language Reference May 2000 222 End of File Specifier s must be the label of an executable statement in the same program unit in which the READ statement occurs The END s and REC rn specifiers can be present in the same READ statement Error Specifier s must be the label of an executable statement in the same program unit in which the READ statement occurs Input List iolist can be empty or can contain input items or implied Do lists The input items can be any of the following Variables Substrings Arrays Array elements Record fields A simple unsubscripted array name specifies all of the elements of the array in memory storage order with the leftmost subscript increasing more rapidly Implied DO lists are described on Implied Do Lists on page 119 Namelist Directed READ The third and fourth forms of the READ statement are used to read the items of the specified namelist group and grname is the name of the group of variables previously defined in a NAMELIST statement Execution Execution proceeds as follows The file associated with the specified unit is determined The format if specified is established The file is positioned appropriately prior to the data tra
298. st be the label of an executable statement in the same program in which the END FILE statement occurs The program control is transferred to the label in the event of an error during the execution of the END FILE statement Description If you are using the ENDFILE statement and other standard FORTRAN I O for tapes we recommend that you use the TOPEN routines instead because they are more reliable Two endfile records signify the end of tape mark When writing to a tape file ENDFILE writes two endfile records then the tape backspaces over the second one If the file is closed at this point both end of file and end of tape are marked If more records are written at this point either by continued write statements or by another program if you are using no rewind magnetic tape the first tape mark stands endfile record and is followed by another data file then by more tape marks and E statement ona END FIL so on Restrictions u must be connected for sequential access Execution of an direct access file is not defined in the FORTRAN 77 Standard and is unpredictable Do not use an END FILE statement on a direct access file FORTRAN 77 Language Reference May 2000 144 Examples Example 1 Constants END FILE END FILE 2 END FILE UNIT 2 Example 2 Variables LOGUNIT 2 END FILE LOGUNIT END FIL
299. symbolic name of the function must appear as a variable name in the subprogram The value of this variable at the time of execution of the RETURN or END statement in the function subprogram is the value of the function Formal Arguments The list of arguments defines the number of formal arguments The type of these formal arguments is defined by some combination of default type statements IMPLICIT statements and DIMENSION statements The number of formal arguments must be the same as the number of actual arguments at the invocation of this function subprogram A function can assign values to formal arguments These values are returned to the calling program when the RETURN or END statements are executed in the function subprogram Restrictions Alternate return specifiers are not allowed in FUNCTION statements FORTRAN 77 Language Reference May 2000 162 77 provides recursive calls A function or subroutine is called recursively if it calls itself directly If it calls another function or subroutine which in turn calls this function or subroutine before returning then it is also called recursively Examples Example 1 Character function CHARACTER 5 FUNCTION BOOL ARG BOOL TRUE IF ARG LE 0 BOOL FALSE RETURN END In the above example BOOL is defined as a function of type CHARACTER with a length of 5 characters This function when called returns the string
300. t or type ArrayName r constant Example Various type statements HARACTER LABEL 12 Standard 6 COMPLEX STRESSPT 0 0 1 0 INTEGER COUNT 99 Z 1 REAL PRICE 0 0 COST 0 REAL LIST 8 0 0 6 1 0 0 0 0 When you initialize a data type remember the following restrictions For a simple variable there must be exactly one constant If any element of an array is initialized all must be initialized m You can use an integer as a repeat factor followed by an asterisk followed by a constant In the example above six values of 1 0 are stored into array elements 2 3 4 5 6 and 7 of LIST a Ifa variable or array is declared AUTOMATIC then it cannot be initialized A pointer based variable or array cannot be initialized For example INTEGER Z 4 POINTER x Z Warning issued not initialized Q In this case the compiler issues a warning message and Z is not initialized If a variable or array is not initialized its values are undefined Chapter 4 Statements 251 If such initialization statements involve variables in COMMON and the ansi compiler flag is set then a warning is issued Note Compiling with any of the options db1 r8 i2 or xtypemap can alter the default size of names typed without an explicit size See the discussion in Chapter 2 Restrictions A symboli
301. t is an ordered pair of real or integer EGER EAL 16 and the other is INT FAL 8 or REAL 16 constants where one of the constants is RI EAL 4 RI R The constants are separated by a comma and the pair is enclosed in parentheses The first constant is the real part and the second is the imaginary part A quad bytes of storage Chapter 2 Data Types and Data Items 7 EX 32 uses 32 complex constant COMPLI Example Quad complex constants SPARC only 9501067 603 1 0 2 000 100 329 3 30 4932 9 1 1 10 4932 4 5106 Invalid need second part 1 0 2 0 Not quad complex need a REAL 16 Integer Constants An integer constant consists of an optional plus or minus sign followed by a string of decimal digits Restrictions No other characters are allowed except of course a space If no sign is present the constant is assumed to be nonnegative The value must be in the INTEGER 4 range 2147483648 2147483647 unless compiled with an option that promotes integers to 64 bits in which case the range becomes INTEGER 8 9223372036854775808 9223372036854775807 See Size and Alignment of Data Types on page 31 Example Integer constants 2147483648 2147483649 Invalid too small error message 10 0 9 29002 2 71828 Not INTEGER decimal point not allowed 1E6 Not INTEGER E not allowed
302. t SUNWspro bin If you find the paths your PATH variable is already set to access Sun WorkShop development tools If you do not find the paths set your PATH environment variable by following the instructions in this section To determine if you need to set your MANPATH environment variable 1 Request the workshop man page by typing man workshop 2 Review the output if any If the workshop 1 man page cannot be found or if the man page displayed is not for the current version of the software installed follow the instructions in this section for setting your MANPATH environment variable Note The information in this section assumes that your Sun WorkShop 6 products were installed in the opt directory Contact your system administrator if your Sun WorkShop software is not installed in opt The PATH and MANPATH variables should be set in your home cshrc file if you are using the C shell or in your home profile file if you are using the Bourne or Korn shells To use Sun WorkShop commands add the following to your PATH variable opt SUNWspro bin m To access Sun WorkShop man pages with the man command add the following to your MANPATH variable opt SUNWspro man For more information about the PATH variable see the csh 1 sh 1 and ksh 1 man pages For more information about the MANPATH variable see the man 1 man page For more information about setting your PATH and MANPATH variables to access this rele
303. t 8 OPEN UNIT 8 OPEN 8 In the above example you get sequential access formatted file and no allowance for error during file open If the file fort 8 does not exist before execution it is created The file remains after termination Example 4 Allowing for open errors OPEN UNIT 8 FILE projectA data test ERR 99 The above statement branches to 99 if an error occurs during OPEN Example 5 Allowing for variable length records EN 1 ACCESS DIRECT recl 1 See Direct Access I O on page 272 for more information about variable length records Chapter4 Statements 3 Example 6 Scratch file OPEN 1 STATUS SCRATCH This statement opens a temporary file with a name such as tmp FAAAa003zU The file is usually in the current working directory or in TMPDIR if that environment variable is set 204 FORTRAN 77 Language Reference May 2000 5 The OPTIONS statement overrides compiler command line options OPTIONS qualifier qualifier Description The following table shows the OPTIONS statement qualifiers TABLE 4 4 OPTIONS Statement Qualifiers Qualifier Action Taken NO G_FLOATING None not implemented 4 Enables Disables the 12 option NO F77 None not implemented CHECK ALL Enables the 0 option CHECK NO OVERFLOW None not implemented CHECK NO BOUNDS Disables Enables the 6 opt
304. t allowed in 58 231 type 58 245 file append on open 199 carriage control on all files 268 INQUIRE 180 internal 272 limit on number open 263 names VMS logical 375 376 preattached 269 properties 180 query 180 See also scratch files specifier for opening 199 two access modes for 265 FILE specifier 373 filling with asterisks or spaces hex and octal output 289 first character carriage control 279 FLOAT 329 form feed character 36 FORM specifier in OPEN 200 FORM BINARY 310 FORM PRINT 266 FORMAT 157 386 FORTRAN 77 Language Reference May 2000 summary 265 1i2 28 IACHAR 330 ICHAR 330 IDINT 329 IEEE representation of selected numbers 367 IF 169 170 173 IFIX 329 illegal REAL expressions 373 IMPLICIT 174 implicit none data typing 372 typing 23 implicit data typing 23 INCLUDE 177 376 initial line 17 initialize in BLOCK DATA 372 in COMMON 372 in declaration 372 input commas 300 INQUIRE 180 182 inquire by file 185 by unit 180 185 specifiers summary 181 inquire option ACCESS 182 BLANK 182 defaults 182 DIRECT 182 ERR 182 EXIST 183 FILE 183 FORM 183 FORMATTED 183 IOSTAT 183 NAME 183 NAMED 183 NEXTREC 184 none for permissions 180 NUMBER 184 0 R 5 PENED 4 ECL 184 EQUENTIAL 184 Index 387 function bit manipulation 346 double precision complex 344 intege
305. t can be used in an assigned GO TO or as a format identifier Chapter4 Statements 89 Examples Example 1 Assign the statement number of an executable statement EQ 0 ASSIGN 9 TO K 0 0 IF LB GO TO Example 2 Assign the statement number of a format statement INTEGER PHORMAT 2 FORMAT A80 ASSIGN 2 TO PHORMAT WRITE PHORMAT Assigned a FORMAT statement no FORTRAN 77 Language Reference May 2000 90 Assignment The assignment statement assigns a value to a variable substring array element record or record field v e Parameter Description v Variable substring array element record or record field e Expression giving the value to be assigned Description The value can be a constant or the result of an expression The kinds of assignment statements are arithmetic logical character and record assignments Arithmetic Assignment v is of numeric type and is the name of a variable array element or record field e is an arithmetic expression a character constant or a logical expression Assigning logicals to numerics is nonstandard and may not be portable the resultant data type is of course the data type of v Execution of an arithmetic assignment statement causes the evaluation of the expression e and conversion to the type of v if types differ and assignment of v with the resulting value typed according to the following table Ty
306. t of an inherently multiline group of statements and neither the UNION line nor the END UNION line has any special indication of continuation You do not put a nonblank in column six nor an amp in column one Each field declaration in a map declaration can be one of the following Structure declaration Record Union declaration a Declaration of a typed data field Chapter4 Statements 3 Example Declare the structure STUDENT to contain either NAME CLASS and MAJOR or NAME CLASS CREDITS and GRAD_DATE STRUCTURE STUDENT CHARACTER 32 NAME INTEGER 2 CLASS UNION AP CHARACTER 16 MAJOR END MAP AP INTEGER 2 CREDITS CHARACTER 8 GRAD_DATE END MAP END UNION END STRUCTURE ECORD STUDENT PERSON In the above example the variable PERSON has the structure STUDENT so PERSON MAJOR references a field from the first map PERSON CREDITS references a field from the second map If the variables of the first map field are initialized and then the program references the variable PERSON MAJOR the first map becomes active and the variables of the second map become undefined 254 FORTRAN 77 Language Reference May 2000 VIRTUAL The VIRTUAL statement is treated the same as the DIMENSION statement ENSION statement VIRTUAL a d a d Parameter
307. t specifier is treated identically to an Iw edit specifier The output field for the Iw edit specifier consists of m Zero or more leading blanks followed by Either a minus if the value is negative or an optional plus followed by m The magnitude of the value in the form on an unsigned integer constant without leading zeros An integer constant always has at least one digit The output field for the Iw m edit specifier is the same as for the Iw edit specifier except that the unsigned integer constant consists of at least m digits and if necessary has leading zeros The value of m must not exceed the value of w If m is zero and the value of the item is zero the output field consists of only blank characters regardless of the sign control in effect Example int1 f integer input CHARACTER LINE 8 12345678 READ LINE 12 13 12 I J PRINT I J K END The program above displays 12 345 67 Example int2 f integer output N 1234 PRINT 1 N N N N 1 FORMAT 16 14 12 16 5 END The above program displays 1234 1234 gt 01234 Chapter5 Input and Output 5 Logical Editing L The L specifier is used for logical data items The general form is Lw The Lw edit specifier indicates that the field occupies w positions The specified input output list item must be of type LOGICAL On input
308. tailed knowledge of how VMS structures are implemented If you need to share structures with C you should use the default no x1 Unsupported VMS FORTRAN Most VMS FORTRAN extensions are incorporated into the 77 compiler The compiler writes messages to standard error for any unsupported statements in the source file The following is a list of the few VMS statements that are not supported DEFINE FILE statement DELETE statement m UNLOCK statement m FIND statement REWRITE statement K EYID and key specifiers in READ statements Nonstandard INQUIRE specifiers CARRIAGECONTROL DEFAULTFIL KEYED ORGANIZATION RECORDTYPE Nonstandard OPEN specifiers ASSOCIATEVARIABLI BLOCKSIZE BUFFERCOUNT CARRIAGECONTROL DEFAULTF ILE 378 FORTRAN 77 Language Reference May 2000 DISP OSE EXTENDSIZE INITIALSIZE KEY AXREC OSPANBLOCKS ORGANIZATION RECORDTYPE SHARED USEROPEN The intrinsic function 3DESCR The following parameters on the OPTIONS statement NO G_FLOATING NO F77 CHECK NO OVERFLOW CHECK NO UNDERF LOW NO NO Some of the INCLUDE statement Some aspects of the INCLUDE statement are converted The INCLUDE statement is operating system dependent so it cannot be completely converted automatically The
309. tatement 316 OPEN statement 197 record reference 59 records 58 230 structure 56 244 unions 62 253 T T edit descriptor 289 tab 13 character 36 control 289 format source 18 372 TASKCOMMON directive 21 temporary files 201 terminal I O 279 termination control edit descriptor 304 TMPDIR environment variable 202 top of page 267 two consecutive operators 373 YPE 249 374 type coercing functions 349 field names 58 245 REAL 16 373 type 250 typeless constants 43 numeric constant 373 types array elements 24 files 265 functions 24 summary of 31 U unary or 373 unary operator 71 unconditional GO TO 168 unsupported extensions 378 VOLATILE 256 WwW width defaults for field descriptors 276 word boundary 31 WRITE 257 X constant indicator 43 edit descriptor 289 x1 19 26 34 36 93 374 375 377 xld 377 xtypemap 32 constant indicator 43 edit descriptor 287 zero leading in hex and octal output 289 zero extend functions 350 394 FORTRAN 77 Language Reference May 2000
310. tement Samples Continued Name Examples Comments REWIND REWIND 1 REWIND I REWIND UNIT U IOSTAT I ERR 9 SAVE SAVE A B C SAVE STATIC STATIC A B C STATIC REAL P D Q IMPLICIT STATIC REAL X Z STOP STOP STOP all done STRUCTURE STRUCTURE PROD INTEGER 4 ID 99 CHARACTER 18 NAME CHARACTER 8 MODEL XL REAL 4 COST REAL 4 PRICE END STRUCTURE SUBROUTINE SUBROUTINE SHR A B 9 Alternate return SUBROUTINE SHR A B amp 9 SUBROUTINE SHR A B SUBROUTINE SHR TYPE 5 TYPE A I Compare to PRINT UNION UNION Compare to STRUCTURE MAP CHARACTER 18 MAJOR END MAP MAP INTEGER 2 CREDITS CHARACTER 8 GRAD_DATE END MAP END UNION VIRTUAL VIRTUAL M 10 10 100 VOLATILE VOLATILE V Z MAT INI 362 FORTRAN 77 Language Reference May 2000 Comments Formatted write to a file Formatted write to stdout Array M Implied Do Substring List directed write to a file List directed write to standard output Character constant format Character variable format Switch variable has format number Namelist write Namelist write to a file Unformatted sequential access Unformatted direct access Formatted direct access Internal formatted sequential Internal list directed sequential access 9 Internal direct access TABLE B 1 FORTRAN Statement Samples Continued Examples WRITE 1 2 Y WRITE UNIT 1 FMT 2
311. ters has no practical limit The characters can continue over to a continuation line but that gets tricky Short standard fixed format lines are padded on the right with blanks up to 72 columns but short tab format lines stop at the newline a Ifa Hollerith constant is used with a binary operator it gets the data type of the other operand If you assign a Hollerith constant to a variable and the length of the constant is less than the length of the data type of the variable then spaces ASCII 32 are appended on the right If the length of a Hollerith constant or variable is greater than the length of the data type of the variable then characters are truncated on the right Ifa Hollerith constant is used as an actual argument it is passed as a 4 byte item Ifa Hollerith constant is used and the context does not determine the data type then INTEGER 4 is used Fortran 95 Style Constants The Sun WorkShop Fortran 77 compiler recognizes the Fortran 95 style syntax for integer and real constants that allows literal specification of the size of the data item In Fortran 95 terminology a constant literal may include an optional trailing underscore followed by a kind type parameter FORTRAN 77 Language Reference May 2000 46 In the Sun Fortran 77 implementation the kind type parameter is limited to the digits 1 2 4 8 or 16 and its use specifies the data size in bytes of th
312. tes how blanks are treated Possible values are ZERO and NULL ZERO Blanks are treated as zeroes NULL Blanks are ignored during numeric conversion This is the default STATUS sta The STATUS sta clause is optional sta is a character expression Possible values are OLD NEW UNKNOWN or SCRATCH OLD The file already exists nonexistence is an error For example STATUS OLD NEW The file doesn t exist existence is an error If F 1LE name is not specified then a file named fort n is opened where n is the specified logical unit UNKNOWN Existence is unknown This is the default SCRATCH For a file opened with STATUS SCRATCH a temporary file with a name of the form tmp FAAAxnnnnn is opened Any other STATUS specifier without an associated file name results in opening a file named fort n where n is the specified logical unit number By default a scratch file is deleted when closed or during normal termination If the program aborts then the file may not be deleted To prevent deletion CLOSE with STATUS KEEP The FORTRAN 77 Standard prohibits opening a named file as scratch if OPEN has a FILE name option then it cannot have 8 STATUS SCRATCH option This FORTRAN extends the standard by allowing opening named files as scratch Such files are normally deleted when closed or at normal termination Chapter4 Statements 201 TMPDI
313. th the values of items Printing Files You get a print file by using the nonstandard FORM PRINT in OPEN OPEN FORM PRINT FORTRAN 77 Language Reference May 2000 266 This specifier works for sequential access files only Definition A print file has the following features With formatted output you get vertical format control for that logical unit a Column one is not printed a If column one is blank 0 or 1 then vertical spacing is one line two lines or top of page respectively a If column 1 is it is replaced by a control sequence that causes a return to the beginning of the previous line m With list directed output you get for that logical unit column one is not printed In general if you open a file with FORM PRINT then for that file list directed output does not provide the FORTRAN Standard blank in column one otherwise it does provide that blank FORM PRINT is for one file per call If you open a file with FORM PRINT then that file has the same content as if it was opened with FORM FORMATTED and filtered with the output filter asa If you compile with the oldldo option old list directed output then all the files written by the program do list directed output without that blank in column one otherwise they all get that blank The oldldo option is global The INQUIRE Statement The INQUIRE statement returns PRI
314. that contains the address Variable names appearing on POINTER statements are considered VOLATILE by the compiler The use of pointers is described in Pointers on page 63 Examples Example 1 A simple POINTER statement POINTER P V Here V is a pointer based variable and P is its associated pointer Example 2 Using the LOC function to get an address 621 1 Assign an address via LOC POINTER P V CHARACTER A 12 V 12 DATA A ABCDEFGHIJKL P LOC A PRINT 5 V ROSS END FORTRAN 77 Language Reference May 2000 212 In the above example the CHARACTER statement allocates 12 bytes of storage for A but no storage for V it merely specifies the type of V because V is a pointer based variable You then assign the address of A to P so now any use of V refers to A by the pointer P The program prints an E Example 3 Memory allocation for pointers by MALLOC POINTER Pl X P2 Y P3 2 P1 MALLOC 36 CALL FREE P1 In the above example you get 36 bytes of memory from MALLOC and then after some other instructions probably using that chunk of memory tell FREE to return those same 36 bytes to the memory manager Example 4 Get the area of memory and its address POINTER P V CHARACTER V 12 2 1 P MALLOC 12 END In the above example you obtain 12 bytes of memory from the function
315. the INCLUDE statement begins with the character then it is taken by 77 to mean the absolute path name of the INCLUDE file Otherwise 77 looks for the file in the following directories in this order 1 The directory that contains the source file with the INCLUDE statement 2 The directories that are named in the Iloc options 3 The current directory in which the 77 command was issued 4 The directories in the default list For a standard install the default list is opt SUNWspro lt release gt include 77 usr include For a non standard install to a directory mydir the default list is mydir SUNWspro lt release gt include f 77 usr include The lt release gt varies with the release of the set of compilers These INCLUDE statements can be nested ten deep Chapter4 Statements 177 Preprocessor include The paths and order searched for the INCLUDE statement are not the same as those searched for the preprocessor include directive described under 1 in the Fortran User s Guide Files included by the preprocessor include directive can contain defines and the like files included with the compiler INCLUDE statement must contain only FORTRAN statements VMS Logical File Names in the INCLUDE Statement 77 interprets VMS logical file names on the INCLUDE statement if The 1 6 or vax spec compiler options are set The environment variable LOGICALNAMEMAPP ING is there to defi
316. the POINTER statement are 64 bit INTEGER 8 values See the Fortran Library Reference Manual and the malloc 3F man pages Optimization and Pointers Pointers have the annoying side effect of reducing the assumptions that the global optimizer can make For one thing compare the following Without pointers if you call a subroutine or function the optimizer knows that the call will change only variables in common or those passed as arguments to that call With pointers this is no longer valid since a routine can take the address of an argument and save it in a pointer in common for use in a subsequent call to itself or to another routine Therefore the optimizer must assume that a variable passed as an argument in a subroutine or function call can be changed by any other call Such an unrestricted use of pointers would degrade optimization for the vast majority of programs that do not use pointers General Guidelines There are two alternatives for optimization with pointers Do not use pointers with optimization level 04 Chapter 2 Data Types and Data Items 7 Use a pointer only to identify the location of the data for calculations and pass the pointer to a subprogram Almost anything else you do to the pointer can yield incorrect results The second choice also has a suboption localize pointers to one routine and do not optimize it but do optimize the routines that do the calculation
317. the list optionally specifies array dimensions and initializes with values type v clist v clist Parameter Description type One of the following BYTE CHARACTER CHARACTER n where n is greater than 0 CHARACTER COMP LEX COMP LEX 8 amp COMP LEX 16 COMP LEX 32 5 SPARC only DOUBLE COMPLEX amp INTEGER INTEGER 2 INTEGER 4 INTEGER 8 LOGICAL LOGICAL 1 8 LOGICAL 2 LOGICAL 4 LOGICAL 8 REAL REAL 4 REAL 8 REAL 16 5 SPARC only DOUBLE PRECISION v Variable name array name array declarator symbolic name of a constant statement function or function subprogram name clist List of constants There are more details about clist in the section on the DATA statement type can be preceded by either AUTOMATIC or STATIC Description A type statement can be used to 250 FORTRAN 77 Language Reference May 2000 Confirm or to override the type established by default by the IMPLICIT statement m Specify dimension information for an array or confirm the type of an intrinsic function Override the length by one of the acceptable lengths for that data type A type statement can assign initial values to variables arrays or record fields by specifying a list of constants clist as in a DATA statement The general form of a type statement is type VariableName constant or type ArrayName constan
318. tic arguments to the I O library routines w m d e Parameters As In Gw dEe The definitions for the parameters w m d and e are Chapter 5 Input and Output 275 w and e are non zero unsigned integer constants d and m are unsigned integer constants w specifies that the field occupies w positions m specifies the insertion of leading zeros to a width of m d specifies the number of digits to the right of the decimal point e specifies the width of the exponent field Defaults for w d ande You can write field descriptors A D E F G I L O or 2 without the w d or e field indicators If these are left unspecified the appropriate defaults are used based on the data type of the I O list element See TABLE 5 3 Typical format field descriptor forms that use w d or e include Aw Iw Lw Ow Zw Dw d Ewd Gwd EwdEe Gw dEe Example With the default w 7 for INTEGER 2 and since 161 decimal A1 hex INTEGER 2 M 161 WRITE gt 8 8 FORMAT 2 END This example produces the following output demo 577 1 5 651 MAIN demo a out AAAAAal demo A represents a blank character position The defaults for w d and e are summarized in the following table TABLE 5 3 Default w d e Values in Format Field Descriptors Field Descriptor List Element w d e I 0 Z BYTE 7 2 INTEGER 2 LOGICAL 2 7 2 INTEGER 4 LOGICAL 4 12 5
319. ting A space One line 0 Two lines 1 To first line of next page No advance stdout only not files If the first character of the format is not space 0 1 or then it is treated as a space and it is not printed Chapter5 Input and Output 9 The behavior of the slew control character is if the character in the first column is it is replaced by a control sequence that causes printing to return to the first column of the previous line where the rest of the input line is printed Space 0 1 and work for stdout if piped through asa Example First character formatting standard output piped through asa demo cat slewl f WRITE abcd WRITE efg The blank single spaces WRITE Ohij The 0 double spaces WRITE 1klm The 17 starts this on a new page WRITE T5 nop The 7 starts this at col 1 of latest line END demo 77 silent slewl f demos a out asa lpr demo The program slew1 f produces file slewl out as printed by lpr bed efg hij klmnop This starts on a new page The of nop is obeyed The results are different on a screen the tabbing puts in spaces demo cat slewl out bed efg hij nop This starts on a new page The of nop is obeyed demo See asa 1 The space 0 and 1 and work for a file opened with m Sequential access FORM PRINT FORTRAN 77 Lang
320. trings FORTRAN 77 Language Reference May 2000 272 23 Example Direct access read of the third record of the internal file LINI demo cat intern f CHARACTER LINE 3 14 DATA LINE 1 81 81 DATA LINE 2 82 82 DATA LINE 3 83 83 READ LINE FMT 214 REC 3 PRINT M N END demo 77 silent intern f demo a out 83 83 demo Formatted I O In formatted I O The list items are processed in the order they appear in the list m Any list item is completely processed before the next item is started m Each sequential access reads or writes one or more logical records Input Actions In general a formatted read statement does the following Reads character data from the external record or from an internal file m Converts the items of the list from character to binary form according to the instructions in the associated format m Puts converted data into internal storage for each list item of the list Example Formatted read READ 6 10 A 8 10 FORMAT F8 3 F6 2 Chapter 5 Input and Output Output Actions In general a formatted write statement does the following Gets data from internal storage for each list item specified by the list Converts the items from binary to character form according to the instructions in the associated format
321. tructures You can refer to fields within substructures Example Refer to fields of substructures PRODUCT and SALE from the previous examples are defined in the current program unit wi ECORD SALE JAPAN JAPAN QUANTITY JAPAN ITEM ID H Z ll Chapter 2 Data Types and Data Items 61 Rules and Restrictions for Substructures Note the following a You must define at least one field name for any substructure No two fields at the same nesting level can have the same name Fields at different levels of a structure can have the same name however doing so might be questionable programming practice m You can use the pseudo name FILL to align fields in a record and create an unnamed empty field m You must not include a structure as a substructure of itself at any level of nesting Unions and Maps A union declaration defines groups of fields that share memory at runtime Syntaxes The syntax of a union declaration is UNION map declaration map declaration map declaration map declaration END UNION The syntax of a map declaration is as follows MAP field declaration field declaration field declaration END MAP Fields in a Map Each field declaration in a map declaration can be one of the following 62 FORTRAN 77 Language Reference May 2000 Structure declaration Union decl
322. uage Reference May 2000 280 Example First character formatting file output demo cat slew2 f OPEN 1 FILE slew out FORM PRINT WRITE 1 abcd WRITE 1 efg WRITE 1 Ohij WRITE 1 1klm WRITE 1 75 01058 1 STATUS KEEP END demo 77 silent slew2 f demo a out The program slew2 f produces the file 81682 out that is equal to the file slewl out in the example above Slew control codes 0 1 and in column one are in the output file as n f and r respectively Character Editing A The A specifier is used for character type data items The general form is Alw On input character data is stored in the corresponding list item On output the corresponding list item is displayed as character data If w is omitted then m For character data type variables it assumes the size of the variable m For noncharacter data type variables it assumes the maximum number of characters that fit in a variable of that data type This is nonstandard behavior Each of the following examples read into a size n variable CHARACTER n for various values of n for instance for n 9 HARACTER C 9 EAD A7 C Chapter5 Input and Output 1 The various values of n in CHARACTER C n are
323. ues Division 369 Extreme Values Comparison 369 Bits and Bytes for Intel and VAX Computers 370 Bits and Bytes for 680x0 and SPARC Computers 0 TABLE C 4 TABLE C 5 TABLE C 6 TABLE C 7 TABLE C 8 TABLE C 9 xiv FORTRAN 77 Language Reference May 2000 Preface The FORTRAN 77 Language Reference specifies the FORTRAN 77 programming language and extensions accepted by the Sun WorkShop 6 77 compiler This is a reference manual intended for programmers with a working knowledge of the Fortran language and the Solaris operating environment Multiplatform Release This Sun WorkShop Fortran release supports versions 2 6 7 and 8 of the Solaris SPARC Platform Edition Operating Environment See the Fortran 77 README file fort ran_77 in the Sun WorkShop README s directory for information regarding availability of this release of the 77 compiler on specific platforms or use the command 77 xhelp readme Access to Sun WorkShop Development Tools Because Sun WorkShop product components and man pages do not install into the standard usr bin and usr share man directories you must change your PATH and MANPATH environment variables to enable access to Sun WorkShop compilers and tools To determine if you need to set your PATH environment variable 1 Display the current value of the PATH variable by typing echo SPATH 2 Review the output for a string of paths containing op
324. uf Variable array or array element ios I O status specifier 8 Error specifier statement label iolist List of I O items each a character variable array or array element Description ENCODE is provided for compatibility with older versions of FORTRAN Similar functionality can be accomplished using internal files with a formatted sequential WRITE statement ENCODE is not in the FORTRAN 77 Standard Data are edited according to the format identifier Example HARACTER S 6 T 6 EGER V 3 4 ECODE 6 1 5 V 6 1 DATA S 987654 D F reads the characters of S as 3 integers and stores them into V 1 V 2 6 ORMAT 3 12 6 CODE The DE and V 3 The ENCODE statement writes the values V 3 V 2 and V 1 into T as T then contains 547698 ENCODE on page 121 for more information and a full example Chapter4 Statements 141 ECODE characters 1 See D END The END statement indicates the end of a program unit with the following syntax END Description The END statement Must be the last statement in the program unit Must be the only statement in a line m Can have a label In a main program an END statement terminates the execution of the program In a function or subroutine it has the effect of a RETURN amp In the FORTRAN 77
325. ult Example of mixed mode If R is real and I is integer then the expression has the type real because first I is promoted to real and then the multiplication is performed Rules Note these rules for the data type of an expression If there is more than one operator in an expression then the type of the last operation performed becomes the type of the final value of the expression Integer operators apply to only integer operands Example An expression that evaluates to zero 2 3 3 4 When an INTEGER 8 operand is mixed with REAL 4 operands the result is REAL 8 There is one extension to this a logical or byte operand in an arithmetic context is used as an integer m Real operators apply to only real operands or to combinations of byte logical integer and real operands An integer operand mixed with a real operand is promoted to real the fractional part of the new real number is zero For example if R is real and I is integer then R I is real However 2 3 4 0 is 0 Double precision operators apply to only double precision operands and any operand of lower precision is promoted to double precision The new least significant bits of the new double precision number are set to zero Promoting a real operand does not increase the accuracy of the operand Complex operators apply to only complex operands Any integer operands are promoted to re
326. und the punctuation A logical constant is any form of true or false value such as TRUE or FALSE or any value beginning with T F and so on A null data item is denoted by two consecutive commas and it means the corresponding array element or complex variable value is not to be changed Null data item can be used with array elements or complex variables only One null data item represents an entire complex constant you cannot use it for either part of a complex constant Example NAMELIST input with some null data nam2 f Namelist input with consecutive commas REAL ARRAY 4 4 NAMELIST GRID ARRAY WRITE Input READ GRID W RITE GRID The data for nam2 f is ASGRID ARRAY gt 8 8 8 This code loads 9s into row 1 skips 4 elements and loads 8s into row 3 of ARRAY Arrays Only The forms r c and r can be used only with an array Chapter5 Input and Output 1 The form r c stores r copies of the constant c into an array where r is a nonzero unsigned integer constant and c is any constant Example NAMELIST with repeat factor in data and r RITE Input nam3 f Namelist REAL PSI 10 AMELIST GRID PSI ro N W READ GRID WRITE GRID The input for nam3 f is ASGRID PSI 5 980 The program nam3 f reads the above input and lo
327. ure names for fields in other structures or as variable names The only statements allowed between the STRUCTURE statement and the END STRUCTURE statement are field declaration statements and PARAMETER statements A PARAMETER statement inside a structure declaration block is equivalent to one outside Restrictions for Fields Fields that are type declarations use the identical syntax of normal FORTRAN type statements and all 77 types are allowed subject to the following rules and restrictions m Any dimensioning needed must be in the type statement The DIMENSION statement has no effect on field names m You can specify the pseudo name FILL for a field name The SF ILL is provided for compatibility with other versions of FORTRAN It is not needed in 77 because the alignment problems are taken care of for you It is a useful feature if you want to make one or more fields not referenceable in some particular subroutine The only thing that FILL does is provide a field of the specified size and type and preclude referencing it You must explicitly type all field names The IMPLICIT statement does not apply to statements in a STRUCTURE declaration nor do the implicit 1 J K L M N rules apply m You cannot use arrays with adjustable or assumed size in field declarations nor can you include passed length CHARACTER declarations In a structure declaration the offset of field n is the offset of the preced
328. use the ACC permissions 180 The following table summarizes the INQUIRE specifiers Data Type of Variable CHARACTER CHARACTER CHARACTER INTEGER LOGICAL CHARACTER CHARACTER INTEGER CHARACTER LOGICAL INTEGER INTEGER LOGICAL INTEGER CHARACTER CHARACTER INQUIRE Statement Specifiers TABLE 4 1 Form SPECIFIER Variable SPECIFIER Value of Variable ACCESS DIRECT SEQUENTIAL BLANK NULL ZERO DIRECT YES 0 ERR Statement number EXIST TRUE FALSE FORM FORMATTED UNFORMATTED BINARY amp FORMATTED UES 0 IOSTAT Error number NAME Name of the file NAMED TRUE FALSE NEXTREC Next record number NUMBER Unit number OPENED TRUE FALSE RECL Record length NOY UNKNOWN SEQUENTIAL YES UNKNOWN UNFORMATTED indicates non standard for inquire by unit but accepted by 77 indicates non standard for inquire by file but accepted by 77 Chapter4 Statements 181 Also Ifa file is scratch then NAMED and NUMBER are not returned If there is no file with the specified name then these variables are not returned DIRECT FORMATTED NAME NAMED SEQUENTIAL and UNFORMATTED If OPENED FALSE then these variables are not returned ACCESS BLANK FORM NEXTREC and RECL If no file is connected t
329. used primarily as a convenient point for placing a t label particularly as the terminal statement in a DO loop Execution of a E statement has no effect The CON statemen CONTINU TINUE statement is used as the terminal statement of a DO loop the next If the 0 statement executed depends on the DO loop exit condition Example DIMENSION U 100 5 0 DO 1 J 1 100 5 8 U J IF 5 GE 1000000 GO TO 2 CONTINUE STOP CONTINUE Chapter4 Statements 117 DATA The DATA statement initializes variables substrings arrays and array elements DATA nlist clist nlist clist Parameter Description nlist List of variables arrays array elements substrings and implied Do lists separated by commas clist List of the form c c c One of the forms c or r c and c is a constant or the symbolic name of a constant r Nonzero unsigned integer constant or the symbolic name of such constant Description All initially defined items are defined with the specified values when an executable program begins running r c is equivalent to r successive occurrences of the constant c A DATA statement is a nonexecutable statement and must appear after all specification statements but it can be interspersed with statement functions and executable statements although this is non standard Note Initializing a local variable in a DATA statement after an
330. ven though they are not in the character set The exceptions are Control A Control B Control C which are not allowed as data These characters can be entered into the program in other ways such as with the char function a Any ASCII character is valid as literal data in a character string For the backslash character you may need to use an escape sequence or use the x1 compiler option For the newline n character you must use an escape sequence See also TABLE 2 3 Symbolic Names The items in the following table can have symbolic names TABLE 1 2 Items with Symbolic Names Symbolic constants Labeled commons Variables Namelist groups Arrays Main programs Structures Block data Records Subroutines Record fields Functions Entry points The following restrictions apply Symbolic names can be any number of characters long The standard is 6 Symbolic names consist of letters digits the dollar sign and the underscore character _ and _ are not standard Symbolic names generally start with a letter never with a digit or dollar sign Names that start with an underscore _ are allowed but may conflict with names in the Fortran and system libraries Note Procedure names that begin with exactly two underscores are considered special support functions internal to the compiler Avoid naming functions or subroutines with exactly two initial underscores for exam
331. ver from C5 BELL receives 07 hex Control G a bell Example 5 Record assignment and record field assignment STRUCTURE PRODUCT INTEGER 4 ID CHARACTER 16 NAME CHARACTER 8 MODE REAL 4 COST REAL 4 PRICE END STRUCTURE RECORD PRODUCT CURRENT PRIOR NEXT LINE 10 CURRENT NEXT Record to record LINE 1 CURRENT Record to array element WRITE 9 CURRENT Write whole record NEXT ID 82 Assign a value to a field Chapter 4 AUTOMATIC The AUTOMATIC statement makes each recursive invocation of the subprogram have its own copy of the specified items It also makes the specified items become undefined outside the subprogram when the subprogram exits through a RETURN statement AUTOMATIC 1 Parameter Description vlist List of variables and arrays Description For automatic variables there is one copy for each invocation of the procedure To avoid local variables becoming undefined between invocations 77 classifies every variable as either static or automatic with all local variables being static by default For other than the default you can declare variables as static or automatic in a STATIC 5 AUTOMATIC or IMPLICIT statement See also the discussion of the stackvar option in the Fortran User s Guide One usage of AUTOMATIC is to declare all automatic at the start of a function Example R
332. wed in 58 231 size unformatted 375 376 specifier direct access 221 271 374 R R R R E R STOP 243 string assignment 77 concatenate 76 in list directed I O 314 join 76 NAMELIST 319 STRUCTURE 244 structure 56 alignment VMS 376 378 disallowed in NAMELIST 316 dummy field 58 245 empty space 58 fill space 245 name 56 57 245 nested 60 not allowed as a substructure of itself 62 restrictions 57 substructure 60 syntax 56 union 62 253 SU edit descriptor 303 subprogram names 14 SUBROUTINE 247 subscript arrays 51 expressions 52 substring 54 disallowed in NAMELIST 316 NAMELIST 319 substructure 60 map 62 253 union 62 253 successive operators 72 summary I O 265 inquire options 181 suppress carriage return 279 symbolic constant name 14 name 12 14 syntax field Reference 59 INQUIRE statement 180 maps 62 253 NAMELIST input 318 short integer data type 28 integers 39 sign control 303 signed constant 34 signed infinity data representation 366 signs in octal or hex input 288 single spacing 267 size of character string 109 SIZEOF 338 sizes summary of data types 31 skip NAMELIST 321 slash editing 304 list directed input 312 slew control 266 279 SNGL 329 SNGLO 329 Solaris versions supported 1 source line formats 17 lines long 18 tab format 372 SP edit
333. with the 0 or Z field descriptors in the FORMAT writes out values as octal or hexadecimal integers respectively It writes to a field that is w characters wide right justified Example Hex output 161 WRITE gt 8 8 FORMAT 23 END The program above displays A1 161 decimal A1 hex AA1 The letter A appears in output column 2 FORTRAN 77 Language Reference May 2000 288 Further examples are included in the following table TABLE 5 7 Sample Octal Hex Output Value Format Internal Decimal Value External Octal Hex Representation 06 32767 77777 02 14251 04 3 27 A033 04 4 27 0033 06 32767 KEKER 4 32767 7FFF 33 2708 A94 Z6 4 2708 AAO0A94 Z5 3 26 ERER KE The general rules for octal and hex output are Negative values are written as if unsigned no negative sign is printed The external field is filled with leading spaces as needed up to the width w If the field is too narrow it is filled with asterisks If m is specified the field is left filled with leading zeros to a width of m Positional Editing For horizontal positioning along the print line 77 supports the forms Tn TLN TRN nT nX where n is a strictly positive integer The format specifier T can appear by itself or be preceded or followed by a positive nonzero number Tn Absolute Columns This tab reads from the nth column or writes to the nth column If n is miss
334. xecution of a logical assignment statement causes evaluation of the logical expression 6 and assignment of the resulting value to v If e is a logical expression rather than an integer between 128 and 127 or a single character constant then e must have a value of either true or false Logical expressions of any size can be assigned to logical variables of any size Assigning numerics to logicals is allowed All non zero values are treated as TRUE and zero is FALSE This practice is nonstandard however and is not portable Chapter 3 Expressions 81 Example A logical assignment OGICAL B1 1 B2 1 061020 L3 4 B2 Bl Bl 3 L4 TRUE Relational Operator A relational operator compares two arithmetic expressions or two character expressions and evaluates to a single logical value The operators can be any of the following TABLE 3 8 Relational Operators Operator Meaning SLT Less than LE Less than or equal EQ Equal NE Not equal GT Greater than GE Greater than or equal The period delimiters are necessary All relational operators have equal precedence Character and arithmetic operators have higher precedence than relational operators For a relational expression first each of the two operands is evaluated and then the two values are compared If the specified relationship holds then the value is true otherwise it is false Example Relational o
335. y itself is nonstandard Scope The scale factor is reset to zero at the start of execution of each I O statement The scale factor can have an effect on D E F and G edit descriptors FORTRAN 77 Language Reference May 2000 302 Input On input any external datum that does not have an exponent field is divided by 10k before it is stored internally Input examples Showing data scale factors and resulting value stored Data 18 63 18 63 18 63E2 18 63 Format E8 2 3P E8 2 3 lt 2 3P E832 Memory 18 63 01863 18 63E2 18630 Output On output with D and E descriptors and with G descriptors if the E editing is required the internal item gets its basic real constant part multiplied by 105 and the exponent is reduced by k before it is written out On output with the F descriptor and with G descriptors if the F editing is sufficient the internal item gets its basic real constant part multiplied by 10 before it 15 written out Output Examples Showing value stored scale factors and resulting output Memory 290 0 290 0 290 29 29040 Format 25 3 15 3 1P E9 3 F9 3 Display 29 00E 01 2 900E 02 0 029E 04 0 290E 03 Sign Editing SU SP SS S The SU SP and S edit descriptors control leading signs for output For normal output without any specific sign specifiers if a value is negative a minus sign is printed in the first position to the left of the leftmost digit if the value is positive print
336. y the second character of the next record The first character of each record is ignored The equal sign of the assignment statement can have zero or more blanks or tabs on each side of it Only constant values can be used for subscripts range indicators of substrings and the values assigned to variables or arrays You cannot use a symbolic constant parameter in the actual input data Hollerith octal and hexadecimal constants are not permitted Each constant assigned has the same form as the corresponding FORTRAN constant There must be at least one comma space or tab between constants Zero or more spaces or tabs are the same as a single space You can enter 1 2 3 0r1 2 3 or1 2 3 and so forth Inside a character constant consecutive spaces or tabs are preserved not compressed FORTRAN 77 Language Reference May 2000 320 A character constant is delimited by apostrophes or quotes but if you start with one of those you must finish that character constant with the same one If you use the apostrophe as the delimiter then to get an apostrophe in a string use two consecutive apostrophes Example Character constants Asample use in 2 Readas use in 2 Asample don t Read as don t Asample don t Read as don t Asample don t Read as don t A complex constant is a pair of real or integer constants separated by a comma and enclosed in parentheses Spaces can occur only aro

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