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Dpic manual - Electrical and Computer Engineering

1. logval logprod amp amp logval lcompare stringexpr lt stringexpr expression lt expression expression stringexpr lcompare lt compare gt expression lcompare lt compare gt stringexpr lt envvar gt lt name gt suffix lt float gt logexpr location x location y placename lt param gt rand AGE 0 rand expression lt func1 gt expression lt func2 gt expression expression assignlist systemcmd 50 DE DPIC 1 2015 Jun 1
2. P n have to be calculated These points satisfy the following equations P O x 0 P i 1 8 P i 3 4 P i 1 8 X i fori 1 to n 1 P n X n The Circuit macros fitcurve macro performs the required calculations and draws the spline to pass through the given points 3 8 Postprocessor commands and color Arbitrary postprocessor commands can be interspersed with pic statements to achieve effects such as gradient fills clipping and transformations There are two ways of passing commands into dpic output Dpic lines beginning with the backslash N are passed through to the output without modi fication This method works well for TeX statements LaTeX statements and commands to postprocessors that rely on the TeX macro processing The second method is the form command text or command sprintf format expression both of which pass the contents of the string into the output stream without the enclosing quotes The string need not start with a backslash Both of the above methods add considerable power to the pic language but there are two issues The first is that if a postprocessor transformation changes the size of a drawn element the pic processor will not know the new size parameters unless they are explicitly calculated The second is the challenge of designing a single macro that produces appropriate postproces sor code to have identical effect with different postprocessors The Circuit macros library contai
3. dashwid 0 05 dash length for dashed lines ellipseht 0 5 ellipse height ellipsewid 0 75 ellipse width lineht 0 5 height of vertical lines linewid 0 5 length of horizontal lines movewid 0 5 length of horizontal moves movewid 0 5 length of horizontal moves textht 0 assumed height of text 11pt for postscript or PDF textoffset 2 5 72 text justification gap textwid 0 assumed width of text When a value is assigned to the variable scale all of the above values are multiplied by the new value of scale The drawing units are thereby changed but the default physical sizes of drawn objects remain unchanged since on final output dimensions are divided by the scale value In addition the following are unchanged by scale arrowhead 1 arrowhead shape fillval 0 5 fill density linethick 0 8 line thickness in points maxpsht 11 5 maximum allowed diagram height maxpswid 8 5 maximum allowed diagram width scale 1 drawing unit scale factor The variables maxpswid and maxpsht may have to be redefined for large diagrams or landscape figures for example 40 2015 Jun 1 DPIC 1 DPIC 1 Positions position is equivalent to a coordinate pair defined in current drawing units and can be expressed in the following forms Here The current drawing position expr expr pair of expressions separated by a comma position position in parentheses for grouping position position Takes the horizontal value from the first position and the ve
4. PDF code m4postprocessor svg SVG code default code 3 5 2 Perpendiculars The Circuit_macros vperp macro illustrates how m4 macros can extend the pic language The purpose is to generate a pair of values representing the unit vector perpendicular to a given line say define vperp define m4pdx 1 end x 1 start x dnl define m4pdy 1 end y 1 start y dnl m4pdy vlength m4pdx m4pdy m4pdx vlength m4pdx m4pdy The macro can be invoked as vperp A where A is the name of a line Another invocation might be vperp last line First two macros beginning with m4 to avoid name clashes are defined as the x distance dx and y distance dy of the end of the line from the start The macro evaluates to the pair dy dx dy dx dx dy where the denominators are calculated by the macro vlength 3 5 3 Setting directions The pic language defines the concept of the current drawing direction which is limited to up down left and right Two terminal circuit elements for example might have to be drawn in any direction which calls for the ability to define diagrams without knowing their final orientation and to rotate the result at will This capability can be added to the basic pic language by judicious use of macros First instead of specifying positions in the usual way such as in line from x1 y1 to x2 y2 12 for e
5. PSTricks and SVG output Line color can be set using outline outlined string The pic language knows no details about color the string contents must be compatible with the postprocessor For example the predefined colours of LaTeX or Tikz pdf packages can be specified or custom colors can be defined using the command string facility so that the postprocessor will know about them Filling by color is similar using the attribute shaded string and when the object is planar and both the fill and outline colors are the same the two attributes can be combined as colour color colored coloured string in which all four spellings are equivalent Finally the attribute same 36 2015 Jun 1 DPIC 1 DPIC 1 duplicates the properties of the previously drawn object of the same type but with the current default placement In addition to scale changes effected by the scale variable the size of the complete picture can be set by appending one or two terms to the PS line as shown PS x fyl where x and y evaluate to constant values On encountering the PE line the picture width w and height h are calculated If x gt 0 then the picture is scaled so that w x Ifh gt y gt 0 or if x 0 andy gt 0 then the picture is scaled so that h y Horizontal and vertical scaling are not independent Text size line thickness and arrowheads are not scaled The units are inches so for example PS 100 25 4 sets the final picture
6. je mgs Mat x Ce the order matters ng lt float gt lt name gt lt Label gt lt LaTeX gt 2 lt string gt nym lt arg gt lt START gt lt END gt ht height wid width rad radius diam diameter thick thickness scaled from to at with by then continue chop same of the way between and Here st rd nd th last fill filled Mees Boe print copy reset exec sh command define undef undefine rand yf else for do lt endfor gt sprintf lt corner gt ne se nw sw t top top north n b bot bottom bottom south s right r east e left 1 west vw start start end end center centre c lt compare gt f gt lt gt lt param gt 44 2015 Jun 1 DPIC 1 DPIC 1 height ht width wid radius rad diameter diam thickness thick length lt func1 gt abs acos asin cos exp expe int log loge sign sin sqrt tan floor lt func2 gt atan2 max min pmod lt linetype gt solid dotted dashed invis invisible lt colrspec gt color colour colored coloured outline outlined shade shaded lt textpos gt centre cente
7. to avoid m4 changing dpic macro definitions or LaTeX enclose them in single quote pairs Some simple applications of m4 macros are illustrated in the subsections that follow 3 5 1 Branching As an illustration of m4 macros suppose that commands that are specific to the postprocessor must be generated Then the macro ifpgf pgf specific commands other commands 11 for example should expand to its first argument if pgf is to be the postprocessor otherwise it should expand to the second argument To implement this ifpgf is defined in the statement define ifpgf ifelse m4postprocessor pgef 1 2 which tests for equality of the character sequences m4postprocessor and pgf However if m4postprocessor is a macro it is replaced by the macro text before the test is performed and if the macro text is pgf then the first argument of ifpgf is evaluated In the Circuit_macros package m4 is required to read a postprocessor specific file before anything else and that file contains the required definition of m4postprocessor The built in macro ifelse can have multiple branches as illustrated below ifelse m4postprocessor pstricks PSTricks code m4postprocessor pgf TikZ PGF code m4postprocessor mfpic Mfpic code m4postprocessor mpost MetaPost code m4postprocessor xfig Xfig code m4postprocessor postscript Postscript code m4postprocessor pdf
8. with PSTricks output the sequence box shaded lightgray fillstyle hlines linecolor blue hatchwidth 0 5pt hatchsep 5pt hatchcolor red hatchangle 45 produces a hatched multicoloured fill and is equivalent to command pscustom fillcolor lightgray fillstyle hlines linecolor blue command hatchwidth 0 5pt hatchsep 5pt hatchcolor red hatchangle 45 box command 7 One limitation of the pic language is that it lacks the concept of a path composed of different basic curves such as lines splines and arcs Dpic however extends the shaded and outlined directives to linear objects such as lines or splines where the output postprocessor allows Consider for example the following macro define slantbox w 1 h 2 xs 3 ys 4 NE wtxs htys 2 SE w xs htys 2 SW w xs h ys 2 NW wtxs h ys 2 N 0 5 between NW and NE E 0 5 between NE and SE S 0 5 between SE and SW W 0 5 between SW and NW C 0 5 between SW and NE line 5 from N to NE then to SE then to SW then to NW then to N a ee This macro implements a version of the xslanted and yslanted attributes recently introduced for gpic boxes for example box wid 0 1 ht 0 5 xslanted 0 yslanted 0 1 shaded Dandelion outlined black The slantbox macro defines the implied compass corners N S NE Its fifth argument can be used to fill or otherwise specify the line For example the command slantbox 0 1 0 5 0 0 1 shaded Dandelion outlined black
9. 1 to do exec sprintf cli g i Macro arguments are passed verbatim as for example function x y z inside which 1 is replaced by x and 2 is replaced by y z To pass arguments by value use exec sprintf for example exec sprintf function 4g g x y z The recursive calls near the bottom of the sorting algorithm shown are another example dpquicksort a lo hi ix Given array a lo hi and index array ix lo hi 10 10 1 10 2 hi sort a lo hi and do identical exchanges on ix define dpquicksort if 3 gt 2 then pivot 1 2 3 2 loop lo 2 hi 3 lo lt hi loop 1 1lo lt pivot lo lo 1 loop 1 hi gt pivot hi hi 1 if lo lt hi then tmp 1 lo 1 10 1 hi 1 hi tmp tmp 4 10 4 10 4 hi 4 hi tmp if lo lt hi then lo lo 1 hi hi 1 if hi gt 2 then exec sprintf dpquicksort 1 4 2 hi if lo lt 3 then i exec sprintf dpquicksort 1 4 10 3 117 HH HH 3 2 4 Branching Pic has a basic if statement of the form if expression then if true else if false but lacks a case statement Multiple branches can be defined by nested if statements but there is another way The macro define case i exec sprintf g floor 1 0 5 1 adds 1 to its rounded first argument to determine which alternative among the remaining arguments should be executed The semicolon or a newline forces dpic to perform the exec
10. 17 is equivalent to the gpic example The above macro can be modified easily to produce arbitrary polygons for example The color Dandelion is automatically defined for PSTricks by the LaTeX line usepackage dvipsnames pstricks For TikZ PGF try usepackage usenames dvipsnames xcolor usepackage tikz 3 8 3 External files Dpic can send print output to a file operating system permitting using the command print arg gt filename which creates the named file or print arg gt gt filename which appends output to the named file if it exists and creates the file if not If the z option has been invoked or dpic was compiled in safe mode both of these give warning messages rather than writing to the file External files can be used to implement forward referencing For example sometimes the final size of a diagram component is required in order to draw a background object that will be overlaid by the component One solution is to process the diagram twice In the following code fragment an assignment to x is written to an external file so that the required value of x will be known after the file is read on the second pass x lt default value gt print gt gt datafile Make sure the file exists copy datafile On second pass read x lt required value gt draw objects and calculate required value y print sprintf x g y gt datafile Write out the assignment 4 SVG PDF and Postscript outp
11. Q or A Q ne the northeast corner of Q The defined points of enumerated objects inside the block preceded by a dot but make sure there is a space after the dot if it is followed by a number rather than an expression in braces for example A Q ist circle n or better A Q 1 st circle n Language elements The lines defining a picture are separated by newline characters or semicolons New lines are significant except after then else or newline A line is continued to the next if the rightmost character is a backslash Non continuation lines beginning with a period are ignored except for PS and PE lines The pic source may be commented by placing each comment to the right of a character unless the is in a string The language elements include the following A drawing command with optional label for example box or A box A position label definition for example A position An assignment to a variable for example x 5 A direction to change the default for example up Branching is performed by if expr then dotrue else I dofalse The looping facility is for variable expr to expr by incr do I anything The loop variable is incremented by 1 by default otherwise by incr which may be 33 2015 Jun 1 DPIC 1 DPIC 1 a negative expression unless it is preceded by the asterisk in which case the loop variable is multiplied by incr The loop variable may be changed by statements in the loop
12. compatible and other formats SYNOPSIS dpic defghmprstvxz infile gt outfile Typically infile is of the form name pic and outfile is of the form name tex eps pdf fig mp svg OPTIONS none LaTeX drawing output very limited font based drawing capability d PDF output basic strings e pict2e output f Postscript output strings in psfrag format g TikZ pgf output h write help message and quit m mfpic output see mfpic documentation p PSTricks output r raw Postscript output no automatic string formatting s MetaPost output t eepicemu output slightly less limited than LaTeX drawing output v svg output x xfig 3 2 output z safe mode access to external files disabled DESCRIPTION Dpic accepts a tight subset of the pic drawing language accepted by GNU pic some times named gpic or AT amp T pic and emits lower level drawing commands for inser tion into LaTeX documents for processing by the xfig or Inkscape drawing tools or for direct display as encapsulated Postscript PDF or SVG Arbitrary text can be inserted into the output for later formatting and arbitrary commands for the post processor PSTricks Tikz pgf etc can be included Dpic returns EXIT SUCCESS normally 0 if messages no more severe than warnings were generated otherwise EXIT FAILURE normally 1 few pic language extensions unique to dpic are implemented for specific purposes 31 2015 Jun 1 DPIC 1 DPIC 1
13. continue lt EMPTY gt lt primitiv gt optexp 48 2015 Jun 1 DPIC 1 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 stringexpr openblock closeblock openblock optexp lt EMPTY gt expression closeblock elementlist optnl objectwith object with objectwith lt Label gt suffix objectwith nth primobj pair expression expression location shift nth ncount th ncount th last last primobj lt primitiv gt lt string gt wp nye shift lt EMPTY gt shift location shift location location position position position place location factor location factor place placename placename lt corner gt lt corner gt placename lt corner gt of placename Here factor primary 1 primary primary factor placename lt Label gt suffix nth primobj placename lt Label gt suffix 49 DPIC 1 2015 Jun 1 DPIC 1 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 ncount logprod logval lcompare primary placename nth primobj lt float gt nen expression mon expression
14. file is inserted into a latex source file invoking respectively the tikz or pstricks package 42 2015 Jun 1 DPIC 1 DPIC 1 SEE ALSO E S Raymond E S Making Pictures with GNU PIC 1995 In GNU groff source dis tribution http www kohala com start troff gpic raymond ps good intro duction to the pic language with elementary illustrations J D Aplevich Drawing with dpic 2015 http ece uwaterloo ca aplevich dpic dpicdoc pdf Specific discussion of dpic facilities and extensions with differ ences between dpic and GNU pic B W Kernighan B W and D M Richie PIC A Graphics Language for Type setting User Manual 1991 AT amp T Bell Laboratories Computing Science Technical Report 116 The original Unix pic J D Aplevich M4 Macros for Electric Circuit Diagrams in LaTeX Documents 2015 File CMman pdf in the graphics Cireuit macros section of CTAN repositories Extension of the pic language using the m4 macro processor for drawing electric circuits and other diagrams AUTHOR Dwight Aplevich lt aplevich at uwaterloo dot ca gt 43 2015 Jun 1 DPIC 1 DPIC 1 7 Appendix B dpic grammar The tokens recognized by the dpic parser are as shown The tokens in lt gt pairs are generated internally Equated tokens lt NL gt have identical internal value emptyterm lt EMPTY gt terminals lt ERROR gt lt ew con nn nn gen men men mf nn Met VEN gt pe pe G
15. obscure circumstances all pic interpreters have difficulty determining whether the lt character is part of such an expression or is a logical comparison operator Dpic treats lt as a comparison in the expression following if so the form x between and B should be used in such expressions e g if 0 5 between A and B y lt 2 then 5 8 then Versions of gpic up to 1 19 ignore the then keyword so that line gt then up 0 5 draws one line segment and is the same as line gt up 0 5 whereas dpic does not ignore then and draws two line segments Newer versions of gpic also draw two segments 5 9 line spline arrow move Dpic treats the defaults for linear objects consistently with planar objects with respect to the at modifier Versions of gpic up to 1 19 treated them differently In dpic line at Here means line with center at Here In gpic line at Here means line with start at Here In dpic the location corresponding to last line is last line c In gpic the location corresponding to last line is last line start The compass corners of multisegmented linear objects are not precisely defined and they should be used with care 5 10 Arc defaults Gpic and dpic have different algorithms for picking a default radius The best practice is to specify arcs completely There is also ambiguity in the pic language The statement arc cw rad x from A to B does not define a unique arc There are two arcs with centres on opp
16. part but there are minor differences The outputs of gpic and dpic are quite different but both can serve as preprocessors that create diagrams for inclusion in LaTeX documents The pic language is particularly suited for easily creating line diagrams such as electric circuits and many persons use a set of macros called Circuit macros which are processed using the m4 macro processor and Dpic The pic language itself allows macro definitions and both pic and m4 macros will be described Dpic usage will be reviewed some programming examples that illustrate dpic extensions of the pic language will be given and then the differences among pic translators will be itemized particularly the differences between gpic and dpic There had better be a disclaimer The temptation to change the pic language has been resisted most of the time so that valid diagrams can be processed with minimal changes using the original Documenter s Workbench ATT pic with gpic or dpic There are exceptions embedded word processor commands principally but also minor differences in defaults for valid pic input a few gpic constructs that dpic does not implement directly and some dpic extensions that gpic does not implement For details see Section 5 2 Dpic usage In the following items in square brackets are optional and items separated by a vertical line are alternatives To produce tex output for LaTeX PSTricks TikZ PGF mfpic pro cessing dpic op
17. statement before leaving the macro For example case 2 print A print B executes the second alternative the third argument and prints B 3 3 Hiding variables As mentioned in Section 3 1 2 locations inside a block are accessible from outside but the values of variables are not Therefore a block can be used to hide variables internal to a macro as in the following example define rgbtohsv 4 0 5 0 6 0 r 1 g 2 b 3 maxc max max r g b minc min min r g b if maxc minc then 4 0 else if maxc r then 4 pmod 60 g b maxc minc 360 else if maxc g then 4 60 b r maxc minc 120 else 4 60 r g maxc minc 240 if maxc 0 then 5 0 else 5 1 minc maxc 6 maxc 17 The three assignments in the first line of the example ensure that the variables exist when the assignments are performed This is not the full story however Macro arguments are called by name rather than by value should the fourth argument for example be literally x minc then the interior variable minc prevails A block is only a partial solution to the problem of hiding variables and care must be exercised in chosing the names of arguments more robust solution is to call by value using exec thus exec sprintf rgbtohsv g g g h s v exprl expr2 expr3 In this case however the last three arguments remain vulnerable to name clashes
18. thereby controlling the number of loop repetitions Braces occur in several contexts When used independently of other language ele ments as anything the left brace saves the current position and direction and the right brace restores them to the saved values after the enclosed lines have been processed Arbitrary postprocessor commands can be generated using command string which inserts the contents of string into the output The string contents must be compatible with the chosen postprocessor Similarly any line that begins with a backslash is copied literally to the output The line exec string executes the contents of string as if it were a normal input line To execute operating system shell commands use sh string and to read lines from an external file use copy string These commands are disabled by the dpic option z or by a compile time switch The command print expr position string gt string gt gt string prints or appends its argument to the file named in the string on the right or by default to the standard error Printing to a file is disabled by the z option Macros The pic language includes macro definition and expansion using define name anything so that when name appears alone or with arguments as name arg then it is replaced by the contents between the braces in the definition A comma in an argu ment list is ignored within a string or parentheses In this substitution o
19. width apply to arrowhead dimensions The scaled attribute scales the object by expr The postprocessed size of a string is unknown in advance to the pic processor but once known the bounding box dimensions can be specified explicitly as for other drawn objects as shown string wid expr ht expr The thickness of lines defining an object are modified using the environmental variable linethick or the attribute thickness thick expr expressed in points Line thickness is independent of any scaling Solid lines are drawn by default this can be modified with solid invisible invis or with 35 2015 Jun 1 DPIC 1 DPIC 1 dotted dashed ezpr the optional expression in the latter setting the length and distance between dashes or dots The following attributes are for putting arrowheads at the start end or both ends of a linear object lt gt lt gt expr The default for arrow objects is gt The shape parameter expr may be omitted in which case the value of the environment variable arrowhead is used The accepted values of expr are currently 0 1 and 3 with 1 the default The drawing direction of an arc is changed by the attribute ccw cw with ccw the default To fill an object with a shade of gray use the attribute fill expr where a value of 1 means white and 0 means black A linear object defining a path can be filled where the postprocessor allows currently for MF pic MPost PDF PGF PS PSfrag
20. width to 100 mm Printed string text may extend beyond the rectangular boundaries defined by w and h unless the text dimensions have been explicitly set If the final diagram width exceeds the environment variable maxpswid or the height exceeds maxpsht both of which can be changed by assignment then the diagram is scaled as for x and y above Placement of drawn objects An object is placed by default so that its entry is at the current point Explicit placement is obtained with object at position which centers the object at position or object with defined point at position for example arc cw from position to position with c at position A block can also be positioned by reference to a displacement from its lower left corner for example A contents with 0 5 0 2 at position Linear objects are placed by default with the start point placed at the current drawing postion otherwise linear objects are defined using a linespec which is of the form linespec from position to position direction expr linespec linespec linespec then linespec where the second line means that linespecs can be concatenated and the third that 37 2015 Jun 1 DPIC 1 DPIC 1 multisegment linear objects are drawn using multiple linespecs separated by then s an example the following draws a triangle with the leftmost vertex at the current point line up 2 right 1 5 then down 3 then to Here Exceptionally the linespec to po
21. Drawing with dpic Dwight Aplevich 31 August 2015 Contents 1 Introduction svssasesrsiarassnses 2 4 SVG PDF and Postscript out PUT iskredckiesiind PE NESS SE NESS SEERNES he 18 2 Die Ubago 13000 ER DERE 2 4 1 Bounding boxes 18 21 Options 00 sii we KER 3 2 2 Lexical error messages 4 5 Pic processor differences 20 5 1 Command line options 20 3 Dpic programming 4 5 2 Output formats os ss ss 20 S Bloks 2 4 bac ede ed a oes 5 5 3 lines and program generated 3 1 1 Positioning blocks 5 pe GE NE 20 3 1 2 Defining scope 5 DA VE sn dk EE 21 ge Dpie macro 4 oo a e ps 6 5 5 for loop and if bodies 21 3 2 1 Finding roots 7 5 6 Endofline 21 3 2 2 Composing statements 8 Of L ses eee eo Eg 21 3 2 3 Evaluating arguments 8 5 8 then 2 0004 22 3 2 4 Branching 9 5 9 line spline arrow move 22 3 3 Hiding variables 10 5 10 Arc defaults 22 OM LOPE 2 2 6 28 sonra ee 10 DIL DURES pi x oe oY Be EG 22 3 5 M4 macros 11 ble print Aree a bk os 23 351 Branching lt sca apa 11 5 13 command arg 23 3 5 2 Perpendiculars 12 5 14 Operating system commands 24 3 5 3 Setting directions 12 HID COPY oe ctga bbe wo Ted 24 3 6 Subscripts 13 5 16 plot 24 3 6 1 Assigning an array of SIT PALL oe bee ae eee we 24 mumbers 14 5 18 Sealing 2 2 2 80005 25 Bf Opine oc 4 460 e
22. LANGUAGE SUMMARY Input consists of a sequence of lines The first line of a picture is PS and the last is PE with lines between these two converted into low level drawing commands for the postprocessor chosen by the option Lines outside of PS PE pass through dpic unchanged Coordinates Coordinate axes in the pic language point to the right and up The drawing units are inches by default but the statement scale 25 4 at the beginning of the diagram has the effect of changing the units to millimetres Drawn objects The primitive drawn objects consist of the planar objects box circle ellipse the linear objects line arrow move spline and arc which has characteristics of both planar and linear objects block is a pair of square brackets enclosing other objects anything and is a planar object The complete diagram is contained implicitly in a block A string is a planar object similar to a box but the pic language also allows strings to be attached to other objects as overlays in which case they are part of the object The current drawing position Here is always defined Initially and at the beginning of a block Here is 0 0 Similarly the current direction which can be any of up down left right is set as right initially Each drawn object has an entry point and exit point that depend on the current direction The entry point is placed by default at the current position Objects can also be placed explicitly wi
23. ached to an object overlays the object at the center and any height or width attributes apply to the object not the string However the justification attributes ljust and rjust can be applied to the individual strings of a stack over laying an object An independent string is placed with its center at the current point by default or by specifying the position of one of its defined points as for any object for example Animal crackers wid 82 3 72 ht 9 7 72 with sw at Q The placement qualifiers above below ljust rjust place the string above below or justified with respect to the placement point For example Animal crackers at Q ljust above places the string above and textoffset units to the right of Q EXAMPLES Source file example pic documentclass article usepackage tikz begin document PS box dashed Hello World PE end document The command dpic g example pic gt example tex pdflatex example produces example pdf containing a dashed box with Hello and World stacked inside To produce a tex file containing PSTricks drawing commands for insertion into a LaTeX document using the input command delete the first three and last lines in the above source and process using the p option of dpic Similarly the picture source PS definecolor puce rgb 0 8 0 53 0 6 box shaded puce PE produces a box filled with a flea like color when processed with dpic g or dpic p and the resulting
24. ae ea 14 5 19 Arrowheads 25 3 7 1 Curve fitting 15 5 20 Compass corners 26 3 8 Postprocessor commands and D21 continue ss we ee a os 26 COIN o eor sos cw ee Kees 15 5 22 Subscripted variables and loca Soe Vor ea cada pwd 16 TONS 24 sda he See a Bs 27 3 8 2 Filling with color 16 523 F les fa ge aan keg s 27 3 8 3 External files 18 524 ATENG saa tee hal es 27 Copyright 2015 J D Aplevich all rights reserved This document version is made available under the Creative Commons attribution licence version 3 0 http creativecommons org licenses by 3 0 you are free to copy and distribute this document provided proper attribution is given by identifying the author 5 25 Vector arithmetic ses 27 5 30 PSTricks anomaly 28 5 26 POSITIONS lt r ae arv avs 27 DAT ABEL ooo arr Ke 28 6 Appendix A dpic man page 31 D28 GREG cut Ga hae d der 28 5 29 Functions 28 7 Appendix B dpic grammar 44 1 Introduction This document is meant for persons using dpic to produce diagrams for LaTeX documents or web files You are assumed to have basic knowledge of the pic language as described for the original Documenter s Workbench ATT pic 3 or the current GNU pic gpic processor 4 However a concise dpic language reference is included here in Appendix and the context free dpic input grammar is given in Appendix B Dpic accepts gpic input for the most
25. age problem concerning arrowheads Let us agree that the following examples should all produce an arrow of length 1 inch and arrowhead width 1 millimetre PS 25 arrow right 1 width 1 25 4 PE PS scale 25 4 arrow right 25 4 width 1 PE PS 1 arrow right 1 4 width 1 25 4 PE The original ATT pic fails on the second example insisting that arrowhead dimensions be given in inches Gpic fails on the third by scaling the arrowhead on final output Although it might be argued that this is a feature it causes serious awkwardness when diagrams are to be scaled to exact final dimensions using the PS x construction since the effective scale factor is unknown until the PE line is processed Dpic generates the same arrow in all three cases treating arrowhead parameters like line thickness unscaled parameters on final output 5 20 Compass corners Dpic consistently requires a dot before compass corners so the gpic line x at center of last box should be written for dpic as x at center of last box 5 21 continue In dpic the continue command appends a linear drawn object to the previous drawn object as if then had been used in the original command but calculations can be performed to determine size or placement of the appended part as in for example line up right calculations continue down more calculations continue up left The keyword continue can also be used slightly differently The line drawn by move to 0 0 line r
26. and should be named with care When as in the example no drawing commands appear in a block then the block has zero size but has position Here so the block can affect the diagram bounding box if Here happens to be outside the bounding box of drawn elements An alternative to this complication is to omit the brackets and rename the local variables to avoid name clashes For example r above could be r rgbtohsv and so on for other variables 3 4 Looping The pic language includes a basic for loop such as the following for x 1 to 10 by 2 do print x but there is no explicit language element except macro recursion for executing a block of code an indefinite number of times However the for variable can be reset within the executable code as in the following example where the first macro argument is printed and doubled repeatedly until it becomes greater than the second argument define series x 1 for i 1 to 2 do if x gt 2 then i 2 else print x x x 2 i 1 10 If this trick seems like an abuse of language it can be disguised somewhat by the definition of a C like loop For example suppose we wish to write loop x 1 x lt 10 x 2 loop y 1 y lt 4 y 1 print x y Then the following defines a suitable mechanism with a loop depth index to allow nesting ld 0 define loop ld_ 1 1 for 1lx__ 1d__ 0 to 1 do if 2 then 1x l1d 1 0 4 3 else 1x__ 1d_ 1 1d__ 1 How
27. ccurrences of 1 are replaced literally by the first argument not by its value if any and so on for other arguments 34 2015 Jun 1 DPIC 1 DPIC 1 The value in a macro is the number of arguments given to the macro dpic ignores white space spaces new lines and tab characters that directly precede an argument in macro invocation macro definition can be deleted by undefine name Macro definitions are global which may require judicious undefinition of macros if there is a risk of name clashes Drawing commands An object is drawn using the following general format Label object attributes placement strings The items following object can occur in any order but the order can make a difference to the drawn result since lines are read and interpreted from left to right Defaults are assumed for all drawing parameters as necessary For example the sequence circle Chew arrow box Swallow line arc cw gt ellipse Digest draws a simple flow diagram using default sizes for all objects with centered words in the circle box and ellipse Attributes An attribute is a keyword or keywords followed by expressions as appropriate Attributes are used to set parameters that control the placement size and appearance of objects The dimension attributes are the following showing valid abbreviations height ht width wid radius rad diameter diam scaled expr When appended to linear objects height and
28. e array x 9 4 7 4 2 0 0 7 9 0 0 10 11 12 13 14 10 assigns the second to sixteenth arguments to x 1 to x 15 respectively Dpic does not define vector operations but it is easy to define macros for them For example macros can be used to define 3 dimensional vectors transform them and to project them onto a drawing plane 3 7 Splines Dpic implements standard pic splines by default as on the left in the following figure which shows the result of the command spline up 1 5 then right 2 then down 1 5 A A straight line is drawn along the first half of the first segment and the last half of the last 14 segment The curve is tangent to the centres of the segments The dpic result of including an expression after spline as in spline x up 1 5 then right 2 then down 1 5 is shown on the right of the figure as the tension parameter x varies from 0 2 to 1 4 The curve begins at the start of the first segment and terminates at the end of the last segment The tension parameter can be varied to assist in fitting a multisegment spline to a curve It turns out for example that the optimum tension for approximating a circle using four splines is the value 0 551784 3 7 1 Curve fitting Splines are drawn with respect to control points but only pass through the first and last point Suppose that a sequence of points X 0 X 1 X n has been given and a spline is to be found to pass through each point The control points P 0 P 1
29. eepic and 1000 for pict2e To see the effect of the slope limitations process the following PS dtor atan2 0 1 180 for d 0 to 360 by 2 do I line from 0 0 to cos d dtor sin d dtor line from 1 2 0 to 1 2 0 line from 0 1 2 to 0 1 2 PE 2 2 Lexical error messages Lexical error messages are generated automatically and state the lexical value that was found and what was expected Some non obvious lexical values are corner a compass corner or c start end envvar environmental variable primitiv box circle ellipse arc line arrow move spline 3 Dpic programming Pic is a simple language with a good ratio of power to complexity so surprisingly sophisticated diagrams can be produced in several areas of application Arbitrary postprocessor commands can be included in the output and several of the postprocessors are powerful drawing languages in their own right so it can be argued that dpic has all the power of these languages However if you find yourself writing extensive postprocessor code then you might ask why you are not programming exclusively in that language Pic is very suitable for line diagrams and recent language extensions allow for basic color Elaborate fills and cropping are the domain of the postprocessors but can be included easily with the use of macros The following sections are intended to help you become familiar with dpic language features Some of these details are exclusive
30. ever loop is a macro so references to arguments in the body will refer to loop arguments which may not be desired In that case use a for loop 3 5 MA macros M4 is a simple but powerful macro language originally distributed with Unix systems 2 but free versions are available for other operating systems The use of this language requires an extra processing step but the power and flexibility of the macros easily make up for it The macro definitions are read before the text to be processed typically by a system command such as m4 library m4 diagram m4 dpic g gt diagram tex An m4 macro is defined as follows define name contents so that distinct occurrences of name will be replaced by contents in the following text This basic description is a vast simplification of the power that results from conditional substitution recursion file inclusion integer arithmetic shell commands and multiple input and output streams The online manual 5 is a good source of details A general rule might be that floating point computation is in the domain of dpic macros but text substitution is often better done in m4 macros When m4 reads text it strips off pairs of single quotes thus text becomes text If text is read again as when it is a macro argument for example then the process is repeated The single quotes serve to delay the evaluation of macros within text as in macro definitions described above Therefore
31. f true else i if false The test for termination of the multiplicative form of the for loop is not identical for dpic and gpic but the effects are identical for positive parameters Both gpic and recent versions of dpic allow the loop index variable to be changed within the loop so infinite repetition or control of termination by a test are possible 5 6 End of line The line end is significant in the pic grammar However dpic ignores line ends following then else or end of line Both the CR octal 015 and NL octal 012 characters are treated as line ends If the last character of a line is but not within a string then reading is continued on the next line Dpic allows this to occur within keywords or constants Strings can contain multiple lines The character begins a comment which ends at the end of the line The construction if condition then if true else i iffalse produces an error with all pic interpreters To avoid this error write if condition then if true else i iffalse 5 7 Logic Dpic and gpic give slightly different default precedences to the logical operators amp amp gt lt lt and gt so judicious use of parentheses may sometimes be in order to guarantee identical behavior In addition put string comparisons in parentheses e g textl text2 21 The construct x lt A B gt is intended to have the same meaning as x between and B but in some
32. fied distances at the ends Truncation values can be negative The attribute by position 38 2015 Jun 1 DPIC 1 DPIC 1 is for positioning for example move by 5 6 Variables and expressions Variable names are alphameric sequences beginning with a lower case letter option ally subscripted as for labels and are defined by assignment For example the fol lowing line defines the variable x if it does not already exist in the current scope x expr The scope of pic variables is the current block in which they are defined including blocks defined later within the current block The assignment X erpr or any assignment using an operator in the set r f requires x to have been defined previously in the current block or an enclosing block Expressions consist of floating point values combined using the unary operator for logical negation and the usual parentheses and binary operators in decreasing order of precedence h amp amp In logical tests the value 0 is equivalent to false and a nonzero value to true with resulting true value of 1 A floating point value is obtained as an integer a number with e syntax a function value a size value of a drawn object for example last box ht or the horizontal or vertical coordinate of a position obtained respectively as position x y The single argument functions are abs acos asin cos exp expe int log loge sign sin
33. for example for i 1 to 10 do exec sprintf A g xAg yhg i 2 i 3 i This effect can also be accomplished with a simple macro 5 29 Functions few additional mathematical functions are defined in dpic abs acos asin expe floor loge sign tan and pmod 5 30 PSTricks anomaly Some time in the mid 2000 to 2010 interval the behaviour of the low level PSTricks command psbezier was changed to match the existing context dependent behavior of the pscurve command within the pscustom environment Dpic does not generate the pscurve com mand but the new behaviour affects dpic defined filled splines The normal PSTricks spline syntax is psbezier x1 y1 x2 y2 x3 y3 x4 y4 However if a correctly defined path containing this spline as its second or later subpath is now enclosed in a pscustom environment the path coordinates are incorrect x1 y1 must be omitted since under these conditions psbezier takes its first coordinate pair to be the current position This anomaly would not be a significant problem if it were always known at the time of generating the psbezier coordinates whether the curve will be enclosed within pscustom but such is not the case The context dependency of pscurve was taken to be a feature rather than a bug An alternative that preserves command orthogonality would have been to define two curve and spline commands for the in pscustom and out of pscustom contexts Such are the difficultie
34. g braces including newlines If the name is given arguments of the form name x y Z then in the macro body n expands to the nth argument which may be nul if at least one argument has been defined and n is a positive integer Otherwise n is not evaluated The line undefine name deletes the macro definition Dpic skips white space immediately preceding macro arguments so that for example name x y Zz is equivalent to name x y z In a macro invocation the arguments are separated by commas An argument may contain commas if they are enclosed within strings or parentheses A double quote character within a string must be preceded by a backslash Thus for example the macro invocation name ABc t DE F has one argument In a dpic macro the value of is the number of arguments given to the macro on invocation Thus if x is a macro name the values of when the macro is invoked as x xQ x 8 x 8 9 and x are respectively 0 1 1 2 and 3 To check whether an argument is null put it in a string for example if 3 then Values internal to a scope can be passed back through macro arguments with the operator thus executing the following define m v 5 1 v 1 y 0 m y gives y the internal value of v Notice that y must be defined prior to macro expansion The use of macros will be illustrated in the following examples 3 2 1 Finding roots A root finder is a p
35. he above fix does not work then for now do not insert spline commands into paths within the pscustom environment unless the spline is the first path segment It is probably safe to say that this anomaly does not occur very often but it can cause considerable difficulty when it does the cure is to update your PSTricks files Legacy diagrams can often be treated in the following way if pstricks97 tex is available on your machine as in Mik TeX distributions for example Replace the line usepackage pstricks with usepackage 97 pstricks or input pstricks97 tex However this method precludes using the newer PSTricks facilities References 1 J D Aplevich M4 macros for electric circuit diagrams in latex documents 2015 Avail able with the CTAN Circuit macros distribution http www ctan org tex archive graphics circuit_macros doc CMman pdf 2 B W Kernighan and D M Richie The M4 macro processor Technical report Bell Laboratories 1977 3 B W Kernighan and D M Richie PIC A graphics language for typesetting user manual Technical Report 116 AT amp T Bell Laboratories 1991 29 4 E S Raymond Making pictures with GNU PIC 1995 In GNU groff source distribution also http www kohala com start troff gpic raymond ps 5 R Seindal et al GNU m4 1994 http www gnu org software m4 manual m4 html 30 DPIC 1 DPIC 1 6 Appendix dpic man page NAME dpic convert pic language input to LaTeX
36. ight 1 then to Here 2 1 terminates at 0 1 since Here is the position 0 0 whereas the following terminates at 1 1 since Here is 1 0 move to 0 0 line right 1 continue to Here 2 1 Input parsing would be possible if continue were to be replaced by then move to 0 0 line right 1 then to Here 2 1 The keyword continue would not have been necessary but it has been retained for historical compatibility 26 5 22 Subscripted variables and locations Dpic allows subscripted variables and positions as an aid in geometric calculations such as fitting splines to a set of points Thus Pos expression is a valid name for a position The rounded integer value of the expression is used Similarly x expression is a valid variable name There are no array operations but it is easy to write macros for them 5 23 Splines Gpic extends the ATT pic grammar to make line 0 5 legal and mean a line of length 0 5 in the current direction All linear objects are treated similarly Dpic does the same except for splines In the statement spline x from A to B then to C the parameter x is a tension parameter normally between 0 and 1 to control the spline curvature If x is not present as in the normal pic grammar the curve starts with a straight line halfway along the first segment and ends with a straight line along the second half of the last segment However when is present dpic draws the spline from the start of the fir
37. in a string are output as U to produce U when processed by LaTeX In a macro a dollar sign followed by an integer in a string will expand to the corresponding macro argument if it is defined Separate the dollar sign from the integer to avoid expansion as in the TeX strings 1 1 or 0 for example Both dpic and gpic allow logical comparison of strings Put the comparison in parentheses String height and width are unscaled on final output from dpic since these depend on later formatting by LaTeX 5 12 print arg Dpic allows only one argument which may be an expression position or string To print several quantities at once use print sprintf to generate a string and if the string is complicated remember that string string2 evaluates to one string 5 13 command arg Arbitrary commands are sent to the standard output stream Dpic allows only one argument which is a string or sprintf 23 5 14 Operating system commands With dpic the required form for a shell operating system command is sh shell command or sh sprintf format expression The value returned by the operating system can be captured by putting the command in parentheses for example if sh shell command 0 then 5 15 copy Dpic supports the command copy filename but does not directly support the commands copy filename thru X body X until word copy filename thru macro until
38. ion The Circuit macros library ver sion operates essentially as above but avoids name clashes by appending the value of the first argument to the internal names somewhat more sophisticated use of a root finder is shown at the right Drawing the spiral on the surface of the sphere requires knowing the points of transi tion of the curve from visible to hidden and back A root finder provides a method that is both simple and adaptable to other shapes The source file Spiral m4 makes use of both m4 macros and pic macros 3 2 2 Composing statements Dpic macro arguments can be expanded almost anywhere Suppose that circles A and B have been defined with intersections at positions AB and BA found using the macro cintersect from Circuit macros for example Then the boundary of the region within both circles might be drawn using the macro shown invoked as lozenge A B AB o define lozenge f A arc from 1 2 to 2 1 with c at 2 BA arc from 2 1 to 1 2 with c at 1 shade 0 5 lozenge A B 3 2 3 Evaluating arguments A macro argument is referenced as n where n must be an integer and may not be an integer expression Consequently the following does not work in a dpic macro for i 1 to do cli i Instead use the dpic statement exec string which executes the contents of string as if it were the current input line Since sprintf format expression behaves like a string the following works for i
39. logprod forhead for assignlist to expression do forincr lt EMPTY gt do do by expression do by by by Wy redirect lt EMPTY gt 47 2015 Jun 1 DPIC 1 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 resetlist systemcmd defhead sprintf exprlist object openblock block DPIC 1 lt compare gt stringexpr lt compare gt lt compare gt stringexpr lt envvar gt resetlist lt envvar gt sh stringexpr define lt name gt define lt Label gt sprintf stringexpr sprintf stringexpr exprlist expression expression exprlist block object height expression object width expression object radius expression object diameter expression object thickness expression object scaled expression object lt directon gt optexp object lt linetype gt optexp object chop optexp object filled optexp object lt arrowhd gt optexp object then object cw object ccw object same object stringexpr object by position object from position object to position object at position object lt textpos gt object lt colrspec gt stringexpr objectwith at position objectwith lt corner gt at position objectwith pair at position
40. mands can be used to enlarge the bounding box as illustrated at the end of the discussion below Dpic uses the constant width Courier font in pdf files which allows the width of strings to be calculated from their height which is specified by textht with default 11 pt or by the height number attribute The string width is calculated from the height and character count but can be set explicitly by using width number as the rightmost string attribute Psfrag output is another special case If textht is set to a nonzero value then its value relative to 11 bp is given as a scale factor to the psfrag tex command An alternative way of changing the diagram text height is to set it in the main document for example small includegraphics file eps Postscript bounding bores For a while the dpic BoundingBox output line simply gave the nominal bounding box determined by line ends and other control points The use of dpic in server mode has induced a change that correctly defines the bounding box for very basic diagrams More explicitly consider PS box with sw at 0 0 PE which draws a box with southwest corner line centres intersecting at Postscript coordinates 0 0 and northeast intersection at 54 36 Dpic r augments this nominal bounding box by half of the last linethick value default linethick is 0 8 bp in the outermost diagram scope to produce the Postscript bounding box definitions hBoundingBox 1 1 55 37 hHiResBoundingB
41. n be added by explicitly writing outlined string shaded string The original pic language did not include the outlined or shaded attributes Current pro cessors recognize these but know nothing about color except as strings attached to drawing elements What the string should contain depends on the postprocessor 3 8 2 Filling with color Basic pic shapes such as boxes circles and ellipses can be colored and filled using for example ellipse shaded color outlined color and if the two colors are the same this can be abbreviated as ellipse colored color where the color strings are compatible with the postprocessor For example the definitions define gold_ 1 0 84 0 ifelse m4postprocessor pstricks 16 command Ndefinecolor gold rgb gold_ m4postprocessor pgf command Ndefinecolor gold rgb gold_ m4postprocessor mpost define gold gold_ m4postprocessor postscript define gold 1 0 84 0 m4postprocessor pdf define gold 1 0 84 0 allow the command circle shaded gold to work for the three different postprocessors specified plus direct postscript or PDF output Alternatively the m4 macro rgbstring fraction fraction fraction evaluates to a string com patible with the postprocessor so that the following produces the same result circle shaded rgbstring 1 0 84 0 More elaborate options can also be invoked For example
42. ner of the block e g Q B A arc circle with 0 5 0 2 at position Reference to a defined point may correspond to drilling down through several block layers as the second example above shows 3 1 2 Defining scope Variables defined within a block are accessible only within the block itself or its sub blocks Thus the statement x 5 creates the variable x and assigns it a value If the statement is x 5 then x must already have been defined either in the block or in a scope containing the block Limiting the scope to a block avoids name conflicts but occasionaly results in subtle behavior The code x 5 x x 2 print x print x prints 7 on the first line and 5 on the second because the assignment within brackets creates variable x with scope within the brackets However Dpic allows a second line of the form x 2 print x which changes the previously defined variable x and the value 7 is printed twice Locations inside a block are accessible from outside as shown in the previous section but the values of variables are not thus an error results from Q v 5 y o The assignment operator in v 0 Q Lv 5 y vw works around this problem but this method requires the internal name v to be known and defined in advance of the block Variable values can be exported by the use of macro arguments as shown later in Section 3 2 or if you must by using the following trick Q v 5 w 6 Origin 0 0 Exp
43. ns several routines that produce equivalent or nearly equiv alent results for several postprocessors It is probably a good rule to stick with one or two postprocessors such as Tikz pgf or PSTricks 15 Dpic defines a number of internal variables for controlling actions that depend on output format Internal variables optTeX opttTeX optpict2e optPSTricks optPDF optPGF optMFpic optPS optPSfrag optMpost optSVG and optxfig have numerical values 1 to 12 respectively and variable dpicopt is given the value corresponding to the output format specified on the command line Therefore conditional drawing with a case statement as described on page 9 or with if as in the following can be performed if dpicopt optPS dpicopt optPDF then drawing commands for postscript or pdf else drawing commands for latex related formats The variable optsafe is set to true if option z has been specified or if dpic has been compiled to allow only safe mode 3 8 1 Color From version 18 gpic allows coloured lines and filled objects as follows and dpic allows them where the postprocessor supports them object outlined string object shaded string object colored string where string specifies a colour compatible with the postprocessor For planar objects the third case is equivalent to object outlined string shaded string For the linear objects line arrow spline dpic treats colored string to be the same as outlined string but fill ca
44. older versions 5 1 Command line options They are completely different of course Type dpic h to see a list of dpic options 5 2 Output formats Gpic t output consists of a sequence of special statements contained in the TeX box box graph The special statements are automatically copied into the dvi file for interpretation by a printer driver such as dvips Dpic does not generate tpic specials See the option list in Section 2 for output formats 5 3 lines and program generated pic Gpic passes lines beginning with through to the output thereby allowing arbitrary Troff macros to be interspersed with pic drawing commands Some programs that generate pic output automatically insert the Troff line ps 11 on the assumption that the text point size should be 11 Dpic ignores non continuation lines beginning with within pictures Some programs e g pstoedit add Troff comment lines beginning with outside the PS PE delimiters These lines must be dealt with separately 20 5 4 lines Both gpic and dpic pass lines beginning with N to the output but dpic does not automatically append a at the end as gpic does 5 5 for loop and if bodies In gpic a for loop has the form for variable exprl to expr2 by expr3 do X body X where X is any character not occurring in body but body is also allowed In dpic only the latter is allowed Similarly the required form of an if statement for dpic is if expr then i i
45. ort v w v Q Export x Q Origin x w Q Export y Q Origin y This method works because all locations Origin and Export inside the block will be trans lated by the same amount no matter where the block is positioned 3 2 Dpic macros Macros can be used to turn the basic dpic language into a powerful tool for producing line drawings macro serves to e specialize the pic language in order to draw components from an application area e abbreviate long sequences of repetitive commands e substitute particular values in commands by the use of macro arguments e provide conditional text replacement depending on the value of its arguments e provide recursive looping Macro definitions are not local to blocks so care must be taken to avoid conflicts with macro names The pic language includes basic macro facilities but the m4 macro processor 2 5 makes a good companion to the language so both will be mentioned General purpose macro defi nitions can be stored in files external to the diagram source and read in automatically In particular the author has written a package called Circuit macros for drawing electric circuits and other diagrams using dpic and m4 1 from which examples will be taken dpic macro is defined by the statement define name contents where name may begin with a lowercase or uppercase letter Then any separate appearance of name in the following lines is replaced by the characters between the definin
46. osite sides of the line joining A and B that satisfy this specification and the interpreter will choose one Instead use arc cw from A to B with c at C 5 11 Strings Strings are arbitrary character sequences between double quotes with double quotes in strings preceded by the backslash character Equivalently a string is produced by the C like sprintf 22 function sprintf format expression The C sprintf function is used for implementing this therefore the precision of default formats such as 4g may vary by machine and compiler To produce transportable results specify the precision completely e g 8 5f As in C the pair in the format string prints the percent character Only the f e g formatting parameters are valid since expressions are stored as floating point numbers e g line sprintf g g0 2 0 above is equivalent to line 200 above Similarly command sprintf pscircle 4g hg hg 0 0 0 5 places the formatted string into the output The numerical sprintf arguments can be arbi trary expressions rather than the constants shown Dpic allows strings to be concatenated by the operator thus abc sprintf def g 2 is equivalent to abc def2 Both dpic and gpic treat N as an escape character prior to the quote character in a string so is a length one string containing the double quote Otherwise the backslash is an ordinary string character For example the characters U
47. owerful tool for determining where lines or curves intersect in diagrams and can be implemented using a macro Consider the trivial example in which we wish to find the root of z 1 between 0 and 2 First define a macro called bisect by reading in a library file containing definitions using a command such as copy filename or by writing a definition such as given below which employs the method of bisection a suitably robust but not particularly fast algorithm Define the two argument macro corre sponding to the function of which we want to calculate the root define parabola i 2 1 72 1 In general many statements might be required to calculate the function but the essential statement is to assign the function value to the name given by the second argument Then call the bisect macro using a command such as bisect parabola 0 2 1e 8 x where the second and third arguments define the search interval the fourth argument specifies the solution precision and the fifth argument is the name of the variable to be set to the root basic version of bisect is given by define bisect x_m 2 x_M 3 x_c x_m x_M 2 if abs x_m x_M lt 4 then 5 x_c else I 1 x m f m 1 x c f c if sign f_c sign f_m then i bisect 1 x c x M 4 5 else bisect 1 x m x c 4 5 VA This macro repeatedly calls parabola and then itself halving the search interval until it is smaller than the prescribed precis
48. ox 0 4 0 4 54 4 36 4 The BoundingBox line contains integer values that enclose the high resolution coordinates PDF bounding boxes PDF includes a MediaBox element which serves approximately the same purpose as the postscript BoundingBox and is calculated the same way By default dpic puts the lower left corner of PDF output at coordinates 0 0 Manual bounding bor adjustment It may be necessary to adjust the bounding box manually To zero the automatic adjustment put linethick 0 at the end of the outermost scope Then arbitrary margins can be added to the nominal box as shown below where 2 1 1 and 0 points are added to the left bottom right and top margins respectively 19 PS Diagram drawing commands linethick 0 move from Diagram sw 2 1 72 scale to Diagram ne 1 0 72 scale PE 5 Pic processor differences Differences among processors and between dpic and gpic particularly are summarized below Normally the only changes required to process correct pic or gpic input with dpic are changes to i instead of X X syntax as explained below together with text formatting if the original code was written for groff The remaining differences documented below are small syntactical differences or relate to the use of PSTricks or the other dpic output formats Sometimes differences in default syntax such as for arcs must be considered Gpic is being actively maintained so some of the items below apply only to
49. r ljust rjust above below lt arrowhd gt a lt gt lt directon gt up down right left lt primitiv gt box circle ellipse arc line arrow move spline lt envvar gt arcrad arrowht arrowwid boxht boxrad boxwid circlerad dashwid ellipseht ellipsewid lineht linewid moveht movewid textht textoffset textwid lt lastsc gt marker for last scaled env var arrowhead fillval linethick maxpsht maxpswid scale lt lastenv gt marker for last env var The expanded dpic grammar follows 0 METAGOAL input lt EOF gt 1 input lt EMPTY gt input picture NL 3 picture start NL elementlist lt END gt 4 start NL elementlist NL lt END gt 5 NL 6 lt ERROR gt 7 start lt START gt 8 lt START gt term 45 2015 Jun 1 DPIC 1 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 DPIC 1 lt START gt term term elementlist lt EMPTY gt element elementlist NL element term factor term x factor term factor term factor element namedobj lt Label gt suffix position assignlist lt directon gt lt LaTeX gt command lbrace elementlist optnl ifpart elsehead elementlist optnl for command s
50. res into web documents or for further processing by the Inkscape graphics editor for which SVG is the native format When the SVG output is used directly in a web document then any required text formatting generally must be included explicitly The other possibility for SVG output is that an SVG library of elements can be drawn with dpic and Inkscape used to place and connect copies of the elements Then Inkscape can export the graphics as eps for processing by TFX or as pdf for processing by pdflatex Inkscape will also export a tex file from which labels can be formatted and overlaid on the imported eps or pdf In all cases arbitrary postprocessor commands that is arbitrary PSTricks SVG Postscript or other commands can be inserted into the dpic output directly from the source This possibility adds considerable power for manipulating diagram elements The z option disables the commands that access external files These commands can be permanently disabled by the use of a compile time option The file Examples txt contains a minimal example of each of these options except z Consult the appropriate manual for processing mfpic PSTricks MetaPost pgf or psfrag output Invoking dpic without options produces basic LaTeX drawing commands by default LaTeX line slopes for example are very limited and you must ensure that lines and arrows are drawn only at acceptable slopes Dpic sets the maximum slope integer to be 6 for LaTeX 453 for
51. rtical value from the second position position Vector addition position expr Scalar postmultiplication Label The label of a defined position or object The position is the center of the object expr of the way between position and position The example x between A and B is equal to A 1 x B x Any value of expr is allowed expr lt position position gt An abbreviated equivalent of the previous form number st rd nd th last object An object within the current block enumerated in order of definition The object is one of line move arrow arc box ellipse circle spline The number can be replaced by I expr For example last means the last string and 272 nd means the fourth block in the current scope The position is the center of the object Parentheses may be required when composite positions or expressions are used in the above forms Finally a position can be given as object defined point Strings A string is a sequence of characters enclosed in double quotes To include a double quote in a string precede it with a backslash Strings can be concatenated using the operator The C like function sprintf format string expr is equivalent to a string Expressions are floating point values so the only applicable number formats are e f and g 41 2015 Jun 1 DPIC 1 DPIC 1 Multiple strings such as terti tezt2 are stacked and centered vertically A string att
52. s of software library maintenance 28 Dpic always generates four or more coordinate pair arguments as in the normal syntax some times resulting in the addition of an extraneous path segment produced within pscustom For some versions of PSTricks a workaround for the problem has been to insert a PSTricks patch in your LaTeX code if you are enclosing splines within pscustom commands More recent versions of the PSTricks package have changed again but starting from the August 27 2010 pstricks tex distribution file a parameter noCurrentPoint has been introduced which prevents psbezier and other commands from taking the current point as the first coor dinate pair The following line inserted into a latex document avoids an error message if the PSTricks version is August 2010 or later psset noCurrentPoint Older versions of PSTricks are handled using the following workaround command makeatletter ifundefined ifPst noCurrentPoint ifundefined MPS Patch gdef MPS Patch typeout Dpic p patching psbezier in pstricks tex some versions def psbezier ii addto pscode ifshowpoints true else false fi tx 0penBeziery ifshowpoints tx BezierShowPoints fi end 0pen0bj ifundefined MPS PatchMsg gdef MPS PatchMsg typeout Dpic p Setting noCurrentPoint to use all coord pairs HH psset noCurrentPoint makeatother This patch need only be executed once per LaTeX run rather than with every diagram If t
53. sition to position to is multiple and does not require the then keyword A single expr is also an acceptable linespec immediately after a linear object and means that the object is drawn to length expr in the current direction The exception to this is spline expr linespec for which the expr is a spline tension parameter If expr is omitted a straight line is drawn to the midpoint of the first two spline control points and from the midpoint of the last two to the last point the spline is tangent to all midpoints between control points If expr is present the spline is tangent at the first and last control points and at all other midpoints and the spline tension can be adjusted Tension values between 0 and 1 are typical In cases where all of the points of a multisegment linear object are not known in advance or inconvenient to calculate the drawing command continue linespec will append a segment to the previously drawn linear object as if continue were then with two differences Arbitrary calculations may be done between the previous object and the continue statement and the current point is the exit point of the previous object The construction line from position to position chop expr truncates the line at each end by the value of expr or if expr is omitted by the current value of environment variable circlerad Otherwise line from position to position chop expri1 chop expr2 truncates the line by the two speci
54. sqrt tan floor The functions exp and log are base 10 The function rand delivers a random number between 0 and 1 and rand expr initializes the random number generator The two argument functions are atan2 max min pmod where pmod is the modulo function delivering a positive value 39 2015 Jun 1 DPIC 1 DPIC 1 Predefined variables The following variables are predefined on invocation of dpic optTeX opttTeX optPict2e optPSTricks optPDF optPGF optMFpic optPS optPSfrag optMpost and optSVG Variable dpicopt is set according to the output option cho sen so that if one of options p or g has been invoked for example then the test if dpicopt optPSTricks dpicopt optPGF then will selectively execute its body statements In addition variable optsafe has value true if the z option has been selected or dpic has been compiled in safe mode Predefined environment variables set of environment variables establishes the default values of drawing parameters within the scope of the current block Their values are inherited from the superior block but can be changed by assignment They can be used in expressions like other variables The variables their default values and default uses are given below arcrad 0 25 arc radius arrowht 0 1 length of arrowhead arrowwid 0 05 width of arrowhead boxht 0 5 box height boxrad 0 radius of rounded box corners boxwid 0 75 box width circlerad 0 25 circle radius
55. st segment to the end of the last segment 5 24 Arithmetic In an expression gpic allows terms of the form x y whereas dpic produces an error message Use x y or the equivalent Dpic allows the assignment operators which do not create a new variable but update the value of the variable already defined Thus the assignment x 1 is equivalent tox x 1 5 25 Vector arithmetic The dpic grammar permits the following X Y Z where Y and Z are defined positions Gpic requires X Y Z x Z y Dpic also allows scalar multiplication X Y 2 3 but not X 2 3 Y 5 26 Positions If X is a position then X is a valid position for dpic but not old versions of gpic which gave an error for a between A and B x y Dropping the parentheses to avoid the error gives 27 a between and B x y which is not the same resulting position Use dpic or a recent gpic if you need this construction 5 27 int Gpic int up to version 1 19 computed the floor of its argument rather than the integer part as specified by ATT pic Dpic provides both the floor and int functions but int O does not compute the same value as these versions of gpic int for non integer negative arguments 5 28 exec In dpic the contents of a string can be executed using exec string or exec sprintf format string args as if the string were the next line of input This enables the programmed generation of names and labels
56. te so that box scaled 1 2 produces a box with dimensions scaled by 1 2 and box line scaled 3 circle scaled 0 5 scales all objects within the block by 0 5 The latter can be used in place of setting the scale environment variable when for example different parts of a diagram require different scaling As always line thicknesses are not scaled 5 19 Arrowheads Pic processors provide a limited variety of built in arrowhead shapes Dpic draws arrowheads according to the environment variable arrowhead as shown below arrowhead 0 gt arrowhead 3 gt default Any other value of arrowhead produces the default filled head shown but also results in an a head shape native to the postprocessor in some cases The default value of arrowhead is 1 in conformance with other pic processors Postprocessor parameters can be changed using lines of the form command postprocessor commands Changing the line thickness does not affect arrowhead size parameters which have to be changed explicitly by either of the following methods The line thickness is specified in points but the arrowhead size parameters are in drawing units Method 1 global change within the current block linethick 2 default 0 8 bp arrowht 0 18 default 0 1 in arrowwid 0 09 default 0 05 in arrowhead 0 default 1 arrow Method 2 change only the currently drawn object arrow thick 2 ht 0 18 wid 0 09 gt 0 There is a subtle langu
57. th respect to absolute coordinates or relative to other objects The exit point becomes the new current position Labels A label in pic is an alphameric sequence that starts with an uppercase letter Dpic allows variables and labels to be subscripted thus T and T 5 are distinct labels The value in brackets can be any expression but it is rounded to the nearest integer value A label gives a symbolic name to a position or drawn object for example Post Here 1 2 Bus 23 line right 4 Defined points Once drawn a linear object has defined points start center and end which can be referenced as known positions for example L line line up 0 5 from L c where center has been abbreviated as c The defined points for a planar object are the compass points on its periphery given by 32 2015 Jun 1 DPIC 1 DPIC 1 D S 6 W nNW ne se sw together with center top bottom right left For an arc these points correspond to the circle of which the arc is a part with the addition of start and end A block has defined points similar to a box but can also have others in its interior For the example A circle Q line circle T Q n the defined points are as follows The points of the outer block as if it were a box for example A ne position defined in the block for example A T The defined points of labeled objects inside the block preceded by a dot for example A Q the centre of block
58. tions file pic gt file tex or cat file pic dpic options gt file tex To produce other formats dpic dle f g h m p r s t v x z file pic gt file tex eps pdf mp fig svg 2 1 Options Dpic accepts the following options none Latex picture output very limited font based drawing commands d PDF output e pict2e output f Postscript output with psfrag strings g TikZ PGF output h write out these options and quit m mfpic output p PSTricks output r raw Postscript output s MetaPost output t eepicemu output v SVG output x xfig 3 2 output z safe mode sh copy and print to file disabled The p option produces output for postprocessing by the LaTeX package PSTricks Similarly the g option produces output for the TikZ PGF packages and makes pdf production via pdflatex a one step process Mfpic and MetaPost output are provided for compatibility The r option produces Postscript eps files in which font changes or typesetting must be done explicitly The f option writes Postscript strings in psfrag format for tex or latex typesetting The d option produces PDF files This format is most useful for diagrams containing graphics only since there is no simple way to change or manipulate fonts for labels The Courier fixed width font is employed by default To produce PDF files containing significant text content use an option such as TikZ with pdflatex The v option produces SVG for inserting figu
59. to dpic and are not described in the GNU manual but are discussed in Section 5 of this document 3 1 Blocks The basic planar objects in pic are box circle and ellipse the placing of which is done according to the current drawing direction or by explicit placement such as box at position which places the object so that its center is at position A block or a composite object is a group of elements enclosed by square brackets such as Q B A arc circle 3 1 1 Positioning blocks A block is placed by default as if it were a box after which the compass points Q n Q sw in the previous example are automatically defined as for a box of the same size and position A block can also be positioned by specifying the location of one of its defined points A defined point is one of the following 1 A compass corner center n ne of the block e g Q B A arc circle with ne at position 2 A defined point of a labeled object or position within the block preceded by a dot e g Q B A arc circle with B A ne at position 3 defined point of an enumerated object in the block preceded by a dot but make sure there is a space after the dot if it is followed by a number e g Q B A arc circle with ist circle at position Even better put braces around the ordinal value which can now be any expression e g with 10 9 th circle at 4 displacement x y from the lower left cor
60. tringexpr exec stringexpr lbrace lt EMPTY gt namedobj object lt Label gt suffix object suffix lt EMPTY gt expression position pair expression between position and position expression of the way between position and position expression lt position position lt compare gt shift assignlist assignment assignlist assignment command print expression redirect print position redirect print stringexpr redirect reset reset resetlist systemcmd copy stringexpr defhead optnl 46 2015 Jun 1 DPIC 1 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 DPIC 1 undefine lt name gt undefine lt Label gt optnl lt EMPTY gt NL ifpart ifhead elementlist optnl elsehead ifpart else for forhead elementlist optnl for forincr lt endfor gt elementlist optnl stringexpr string stringexpr string string lt string gt sprintf assignment lt name gt suffix expression lt name gt suffix assignment lt envvar gt expression lt envvar gt assignment expression term term expression term expression term wou term ifhead setlogic if logexpr then setlogic lt EMPTY gt logexpr logprod logexpr
61. ues if the first and second arguments are not given Then a line is drawn to outline the box and the fill 0 9 argument is appended to the line command to fill the box slightly more elaborate version that encloses the box in brackets is given by the Circuit macros rotbox macro 3 6 Subscripts Dpic allows variables and capitalized labels to have subscripts thus x and x 4 are distinct variable names and can be employed in expressions as usual Similarly P and P 3 are distinct labels 13 3 6 1 Assigning an array of numbers We can assign an array of numbers to subscripted variables using statements such as x 1 47 x 2 63 and so on but generating the subscripts is inconvenient particularly when these statements are obtained by editing a data file One way of entering the data is to employ the m4 macro definition define inx define m4x ifdef m4x incr m4x 1 m4x Then writing x inx 47 x inx 63 and processing with m4 automatically generates the required subscripts The macro sets m4x to 1 if it is not yet defined otherwise it increments m4x and then it evaluates to m4x On completion of the assignments m4x has the value of the last subscript Another way of assigning variables to a subscripted variable is by the definition define array for i 2 to do exec sprintf 1 g 4g i 1 i which equates the subscripted first argument to the values in argument 2 3 so that for exampl
62. ut The r raw Postscript v SVG d PDF and x xfig options of dpic produce output that is not intended to be processed directly by LaTeX or in some cases printed on paper Postscript output can be inserted into a document with the includegraphics macro This command will also import pdf for processing by pdflatex 4 1 Bounding boxes The bounding box of a diagram is not always known exactly or even defined exactly since it can depend on the context in which the diagram is to be used Within a diagram different line widths mitred joints splines colored output over painting arbitrary text arbitrary Postscript or SVG and other complications are allowed consequently dpic can only provide an estimate of the exact bounding box 18 There is apparently no reliable way to know the exact bounding box of arbitrary SVG text so dpic uses an approximation and text placement on diagrams may have to be adjusted by hand Truncated text The dpic textht environmental variable often gives dpic a good estimate of the actual height of embedded text but the width of the text is more difficult to estimate Consequently text is often truncated by the figure bounding box at the left or right edge of the figure Setting the width of strategic strings by hand e g string wid 0 75 often serves as a quick cure in specific cases but is better done automatically as described in the Circuit_macros documentation 1 Otherwise strategic move com
63. word These functions and many more are readily implementable with dpic in any unix like envi ronment For example a basic implementation of copy filename thru macro is given by the following macro copythru macro_name filename Implements copy filename thru macro_name for data separated by comma spaces or tabs define copythru i sh sed e s t 1 e s t e s Will t g 2 gt copy_tmp__ copy copy_tmp__ sh rm f copy_tmp__ The lines of the filename file are changed to calls of the macro name macro and written into a temporary file which is then read by dpic Such usage is not as simple as a built in function but allows greater flexibility of data by customization of the copythru macro to suit 5 16 plot The plot command is deprecated in gpic and not allowed in dpic 5 17 fill In gpic a fill value of 0 means white 1 means black Dpic uses 0 as black and 1 as white as do Postscript and the original ATT pic The pic language specifies fill only for box ellipse and circle but fill is supported by dpic using the shaded directive The concept of a path containing several arbitrary linear objects 24 does not exist in the pic language but can be implemented using postprocessor commands inserted into command string statements Arbitrary paths can also be constructed using a single spline and the continue statement 5 18 Scaling Dpic implements a scaled attribu
64. xample let us agree to write line from vec_ x1 y1 to vec x2 y2 where vec x1 y1 evaluates to a x1 b yl c x1 d y1 Then if a and d are cos theta bis sin theta and c is sin theta this transformation corresponds to rotating the argument vector by an angle theta To produce relative coordi nates the macro rvec x y evaluates to Here vec x y so writing line to rvec x1 y1 draws a line from the current position Here to a point x1 y1 defined with respect to rotated coordinates relative to Here The Circuit macros package makes extensive use of versions of the above two macros The angle and transformation constants are set using macros Point degrees and point radians which have angles as arguments This usage is illustrated by the macro 1box which draws a pic like box oriented in the current direction It can be defined as define lbox define m4bwd ifelse 1 boxwid 1 dnl define m4bht ifelse 2 boxht 2 dnl1 line from rvec_ m4bwd 0 to rvec_ m4bwd m4bht 2 then to rvec 0 m4bht 2 then to rvec 0 m4bht 2 then to rvec m4bwd m4bht 2 then to rvec m4bwd 0 3 The macro is invoked as 1box width height type for example Point 20 lbox fill 0 9 draws a light gray filled box of default size at an angle of 20 degrees from the horizontal In the macro the width and height of the box are first defined using default val

Dpic manual - Electrical and Computer Engineering

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