Provided by: groff-base_1.22.4-8build1_amd64 bug


       pic - compile pictures for troff or TeX


       pic [-nvCSU] [file ...]

       pic -t [-cvzCSU] [file ...]


       This  manual  page  describes  the GNU version of pic, which is part of the groff document
       formatting system.  pic compiles descriptions of pictures embedded  within  troff  or  TeX
       input files into commands that are understood by TeX or troff.  Each picture starts with a
       line beginning with .PS and ends with a line beginning with .PE.  Anything outside of  .PS
       and .PE is passed through without change.

       It  is  the  user's  responsibility  to  provide  appropriate definitions of the PS and PE
       macros.  When the macro package being used does not supply such definitions (for  example,
       old  versions  of  -ms),  appropriate  definitions  can be obtained with -mpic: These will
       center each picture.


       Options that do not take arguments may be grouped behind a single -.  The  special  option
       --  can  be  used  to mark the end of the options.  A filename of - refers to the standard

       -C     Recognize .PS and .PE even when  followed  by  a  character  other  than  space  or

       -S     Safer  mode;  do  not  execute  sh  commands.  This can be useful when operating on
              untrustworthy input (enabled by default).

       -U     Unsafe mode; revert the default option -S.

       -n     Don't use the groff extensions to the troff drawing commands.  You should use  this
              if  you  are  using  a  postprocessor  that  doesn't support these extensions.  The
              extensions are described in groff_out(5).  The -n option also causes pic not to use
              zero-length lines to draw dots in troff mode.

       -t     TeX mode.

       -c     Be  more  compatible with tpic.  Implies -t.  Lines beginning with \ are not passed
              through transparently.  Lines beginning with .  are passed through with the initial
              .  changed to \.  A line beginning with .ps is given special treatment: it takes an
              optional integer argument specifying the line thickness (pen size) in  milliinches;
              a missing argument restores the previous line thickness; the default line thickness
              is 8 milliinches.  The line thickness thus specified takes effect only when a  non-
              negative line thickness has not been specified by use of the thickness attribute or
              by setting the linethick variable.

       -v     Print the version number.

       -z     In TeX mode draw dots using zero-length lines.

       The following options supported by other versions of pic are ignored:

       -D     Draw all lines using the \D escape sequence.  pic always does this.

       -T dev Generate output for the troff device dev.  This is unnecessary  because  the  troff
              output generated by pic is device-independent.


       This  section  describes  only the differences between GNU pic and the original version of
       pic.  Many of these differences also apply to newer versions  of  Unix  pic.   A  complete
       documentation is available in the file


   TeX mode
       TeX  mode  is enabled by the -t option.  In TeX mode, pic will define a vbox called \graph
       for each picture.  Use the figname command to change the  name  of  the  vbox.   You  must
       yourself print that vbox using, for example, the command


       Actually, since the vbox has a height of zero (it is defined with \vtop) this will produce
       slightly more vertical space above the picture than below it;

              \centerline{\raise 1em\box\graph}

       would avoid this.

       To make the vbox having a positive height and a depth of zero (as  used  e.g.  by  LaTeX's
       graphics.sty), define the following macro in your document:

                 \vbox{\unvbox\csname #1\endcsname\kern 0pt}}

       Now you can simply say \gpicbox{graph} instead of \box\graph.

       You must use a TeX driver that supports the tpic specials, version 2.

       Lines  beginning  with  \ are passed through transparently; a % is added to the end of the
       line to avoid unwanted spaces.  You can safely use this feature  to  change  fonts  or  to
       change  the  value  of \baselineskip.  Anything else may well produce undesirable results;
       use at your own risk.  Lines beginning with a period are not given any special treatment.

       for variable = expr1 to expr2 [by [*]expr3] do X body X
              Set variable to expr1.  While the value of variable is less than or equal to expr2,
              do  body and increment variable by expr3; if by is not given, increment variable by
              1.  If expr3 is prefixed by * then variable will instead be  multiplied  by  expr3.
              The  value  of expr3 can be negative for the additive case; variable is then tested
              whether it is greater than or equal to expr2.  For the multiplicative  case,  expr3
              must be greater than zero.  If the constraints aren't met, the loop isn't executed.
              X can be any character not occurring in body.

       if expr then X if-true X [else Y if-false Y]
              Evaluate expr; if it is non-zero then do if-true, otherwise do if-false.  X can  be
              any  character  not  occurring in if-true.  Y can be any character not occurring in

       print arg...
              Concatenate the arguments and print as a line on  stderr.   Each  arg  must  be  an
              expression, a position, or text.  This is useful for debugging.

       command arg...
              Concatenate  the  arguments  and pass them through as a line to troff or TeX.  Each
              arg must be an expression, a position, or text.  This has a  similar  effect  to  a
              line  beginning  with  .  or  \,  but  allows  the values of variables to be passed
              through.  For example,

                     x = 14
                     command ".ds string x is " x "."


                     x is 14.

       sh X command X
              Pass command to a shell.  X can be any character not occurring in command.

       copy "filename"
              Include filename at this point in the file.

       copy ["filename"] thru X body X [until "word"]
       copy ["filename"] thru macro [until "word"]
              This construct does body once for each line of filename; the  line  is  split  into
              blank-delimited  words,  and  occurrences of $i in body, for i between 1 and 9, are
              replaced by the i-th word of the line.  If filename is not given, lines  are  taken
              from  the  current input up to .PE.  If an until clause is specified, lines will be
              read only until a line the first word of which is word;  that  line  will  then  be
              discarded.  X can be any character not occurring in body.  For example,

                     copy thru % circle at ($1,$2) % until "END"
                     1 2
                     3 4
                     5 6

              is equivalent to

                     circle at (1,2)
                     circle at (3,4)
                     circle at (5,6)

              The  commands  to be performed for each line can also be taken from a macro defined
              earlier by giving the name of the macro as the argument to thru.

       reset variable1[,] variable2 ...
              Reset pre-defined variables variable1, variable2 ... to their default  values.   If
              no  arguments  are  given, reset all pre-defined variables to their default values.
              Note that assigning a value to scale also causes  all  pre-defined  variables  that
              control  dimensions  to  be  reset  to  their default values times the new value of

       plot expr ["text"]
              This is a text object which is constructed by using text as  a  format  string  for
              sprintf  with  an  argument of expr.  If text is omitted a format string of "%g" is
              used.  Attributes can be specified in the same way as for a normal text object.  Be
              very  careful  that  you  specify  an appropriate format string; pic does only very
              limited checking of the string.  This is deprecated in favour of sprintf.

       variable := expr
              This is similar to = except variable must already be  defined,  and  expr  will  be
              assigned  to  variable without creating a variable local to the current block.  (By
              contrast, = defines the variable in the current block if it is not already  defined
              there,  and  then  changes  the value in the current block only.)  For example, the

                     x = 3
                     y = 3
                       x := 5
                       y = 5
                     print x " " y


                     5 3

       Arguments of the form

              X anything X

       are also allowed to be of the form

              { anything }

       In this case anything can contain balanced occurrences of { and }.  Strings may contain  X
       or imbalanced occurrences of { and }.

       The syntax for expressions has been significantly extended:

       x ^ y (exponentiation)
       atan2(y, x)
       log(x) (base 10)
       exp(x) (base 10, i.e. 10^x)
       rand() (return a random number between 0 and 1)
       rand(x) (return a random number between 1 and x; deprecated)
       srand(x) (set the random number seed)
       max(e1, e2)
       min(e1, e2)
       e1 && e2
       e1 || e2
       e1 == e2
       e1 != e2
       e1 >= e2
       e1 > e2
       e1 <= e2
       e1 < e2
       "str1" == "str2"
       "str1" != "str2"

       String comparison expressions must be parenthesised in some contexts to avoid ambiguity.

   Other Changes
       A  bare  expression,  expr,  is  acceptable as an attribute; it is equivalent to dir expr,
       where dir is the current direction.  For example

              line 2i

       means draw a line 2 inches long in the current direction.  The ‘i’ (or ‘I’)  character  is
       ignored; to use another measurement unit, set the scale variable to an appropriate value.

       The  maximum  width  and  height  of the picture are taken from the variables maxpswid and
       maxpsht.  Initially these have values 8.5 and 11.

       Scientific notation is allowed for numbers.  For example

              x = 5e-2

       Text attributes can be compounded.  For example,

              "foo" above ljust

       is valid.

       There is no limit to the depth to which blocks can be examined.  For example,

              [A: [B: [C: box ]]] with .A.B.C.sw at 1,2
              circle at last [].A.B.C

       is acceptable.

       Arcs now have compass points determined by the circle of which the arc is a part.

       Circles, ellipses, and arcs can be dotted or dashed.  In TeX mode splines can be dotted or
       dashed also.

       Boxes  can  have  rounded corners.  The rad attribute specifies the radius of the quarter-
       circles at each corner.  If no rad or diam attribute is given, a radius of boxrad is used.
       Initially, boxrad has a value of 0.  A box with rounded corners can be dotted or dashed.

       Boxes  can  have  slanted  sides.   This  effectively  changes  the  shape of a box from a
       rectangle to an arbitrary parallelogram.  The xslanted and yslanted attributes specify the
       x and y offset of the box's upper right corner from its default position.

       The  .PS  line can have a second argument specifying a maximum height for the picture.  If
       the width of zero is specified the width will be ignored in computing the  scaling  factor
       for  the  picture.   Note  that  GNU  pic  will  always scale a picture by the same amount
       vertically as well as horizontally.  This is different from the  DWB  2.0  pic  which  may
       scale  a  picture  by  a  different  amount  vertically  than  horizontally if a height is

       Each text object has an invisible box associated with it.  The compass points  of  a  text
       object are determined by this box.  The implicit motion associated with the object is also
       determined by this box.  The dimensions of this box are taken from the  width  and  height
       attributes;  if  the  width  attribute  is not supplied then the width will be taken to be
       textwid; if the height attribute is not supplied then the height will be taken to  be  the
       number  of  text  strings  associated with the object times textht.  Initially textwid and
       textht have a value of 0.

       In (almost all) places where a quoted text string can be used, an expression of the form

              sprintf("format", arg,...)

       can also be used; this will produce the arguments formatted  according  to  format,  which
       should  be  a  string  as  described  in printf(3) appropriate for the number of arguments

       The thickness of the lines used to draw objects is controlled by the  linethick  variable.
       This  gives  the  thickness  of  lines  in points.  A negative value means use the default
       thickness: in TeX output mode, this means use a thickness of 8 milliinches; in TeX  output
       mode  with  the  -c  option,  this means use the line thickness specified by .ps lines; in
       troff output mode, this means use a thickness proportional to the pointsize.  A zero value
       means  draw the thinnest possible line supported by the output device.  Initially it has a
       value of -1.  There is also a thick[ness] attribute.  For example,

              circle thickness 1.5

       would draw a circle using a line with a thickness of 1.5 points.  The thickness  of  lines
       is  not  affected  by the value of the scale variable, nor by the width or height given in
       the .PS line.

       Boxes (including boxes with rounded corners or slanted sides), circles and ellipses can be
       filled  by  giving  them  an attribute of fill[ed].  This takes an optional argument of an
       expression with a value between 0 and 1; 0 will fill it with white, 1 with  black,  values
       in  between  with  a  proportionally gray shade.  A value greater than 1 can also be used:
       this means fill with the shade of gray that is currently being used for  text  and  lines.
       Normally this will be black, but output devices may provide a mechanism for changing this.
       Without an argument, then the value of the variable fillval will be used.  Initially  this
       has  a value of 0.5.  The invisible attribute does not affect the filling of objects.  Any
       text associated with a filled object will be added after the object has  been  filled,  so
       that the text will not be obscured by the filling.

       Three  additional  modifiers are available to specify colored objects: outline[d] sets the
       color of the outline, shaded the fill  color,  and  colo[u]r[ed]  sets  both.   All  three
       keywords expect a suffix specifying the color, for example

              circle shaded "green" outline "black"

       Currently,  color  support  isn't available in TeX mode.  Predefined color names for groff
       are in the device macro files, for example ps.tmac; additional colors can be defined  with
       the .defcolor request (see the manual page of troff(1) for more details).

       To  change  the  name  of  the vbox in TeX mode, set the pseudo-variable figname (which is
       actually a specially parsed command) within a picture.  Example:

              figname = foobar;

       The picture is then available in the box \foobar.

       pic assumes that at the beginning of a picture both glyph and fill color are  set  to  the
       default value.

       Arrow  heads  will  be  drawn as solid triangles if the variable arrowhead is non-zero and
       either TeX mode is enabled or the -n option has not been given.  Initially arrowhead has a
       value of 1.  Note that solid arrow heads are always filled with the current outline color.

       The troff output of pic is device-independent.  The -T option is therefore redundant.  All
       numbers are taken to be in inches; numbers are never interpreted to be  in  troff  machine

       Objects can have an aligned attribute.  This will only work if the postprocessor is grops,
       or gropdf.  Any text associated with an  object  having  the  aligned  attribute  will  be
       rotated  about  the  center  of the object so that it is aligned in the direction from the
       start point to the end point of the object.  Note that this attribute will have no  effect
       for objects whose start and end points are coincident.

       In places where nth is allowed expr’th is also allowed.  Note that ’th is a single token:
       no space is allowed between the  and the th.  For example,

              for i = 1 to 4 do {
                 line from ‘i’th box.nw to ‘i+1’th


       To obtain a stand-alone picture from a pic file, enclose your pic code with  .PS  and  .PE
       requests;  roff  configuration  commands may be added at the beginning of the file, but no
       roff text.

       It is necessary to feed this file into groff without adding any page information,  so  you
       must  check  which  .PS  and  .PE requests are actually called.  For example, the mm macro
       package adds a page number, which is very annoying.  At the moment, calling standard groff
       without any macro package works.  Alternatively, you can define your own requests, e.g. to
       do nothing:

              .de PS
              .de PE

       groff itself does not provide direct conversion into other  graphics  file  formats.   But
       there  are  lots  of  possibilities  if  you first transform your picture into PostScript®
       format using the groff option -Tps.  Since this ps-file lacks BoundingBox  information  it
       is  not  very  useful by itself, but it may be fed into other conversion programs, usually
       named ps2other or pstoother or the like.  Moreover, the PostScript interpreter ghostscript
       (gs) has built-in graphics conversion devices that are called with the option

              gs -sDEVICE=<devname>


              gs --help

       for a list of the available devices.

       An  alternative  may  be to use the -Tpdf option to convert your picture directly into PDF
       format.  The MediaBox of the file produced can be controlled by passing a  -P-p  papersize
       to groff.

       As the Encapsulated PostScript File Format EPS is getting more and more important, and the
       conversion wasn't regarded trivial in the past you might be interested to know that  there
       is  a  conversion  tool named ps2eps which does the right job.  It is much better than the
       tool ps2epsi packaged with gs.

       For bitmapped graphic formats, you should use pstopnm; the  resulting  (intermediate)  PNM
       file  can be then converted to virtually any graphics format using the tools of the netpbm


              Example definitions of the PS and PE macros.


       troff(1), groff_out(5), tex(1), gs(1), ps2eps(1), pstopnm(1), ps2epsi(1), pnm(5)

       Eric S. Raymond, Making Pictures With GNU PIC.
       /usr/share/doc/groff-base/ (this file, together with its  source  file,,  is
       part of the groff documentation)

       Tpic: Pic for TeX

       Brian  W.  Kernighan,  PIC    A  Graphics Language for Typesetting (User Manual) ⟨http://⟩.   AT&T  Bell   Laboratories,   Computing   Science
       Technical Report No. 116 (revised May, 1991).

       ps2eps  is  available  from  CTAN  mirrors,  e.g. ⟨

       W.  Richard   Stevens,   Turning   PIC   into   HTML

       W.   Richard   Stevens,   Examples   of   pic  Macros⟩


       Input characters that are invalid for groff (i.e., those with ASCII code 0, or 013  octal,
       or  between  015  and  037 octal, or between 0200 and 0237 octal) are rejected even in TeX

       The interpretation of fillval is incompatible with the pic in  10th  edition  Unix,  which
       interprets 0 as black and 1 as white.

       PostScript® is a registered trademark of Adobe Systems Incorporation.