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PIC(1)                               General Commands Manual                               PIC(1)

NAME
       pic - compile pictures for troff or TeX

SYNOPSIS
       pic [ -nvCSU ] [ filename ... ]
       pic -t [ -cvzCSU ] [ filename ... ]

DESCRIPTION
       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 cen‐
       ter each picture.

OPTIONS
       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
       input.

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

       -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 exten‐
              sions 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.

USAGE
       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 doc‐
       umentation is available in the file

              /usr/share/doc/groff-base/pic.ms.gz

   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 your‐
       self print that vbox using, for example, the command

              \centerline{\box\graph}

       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:

              \def\gpicbox#1{%
                 \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.

   Commands
       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
              if-false.

       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,

                     .PS
                     x = 14
                     command ".ds string x is " x "."
                     .PE
                     \*[string]

              prints

                     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 dis‐
              carded.  X can be any character not occurring in body.  For example,

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

              is equivalent to

                     .PS
                     circle at (1,2)
                     circle at (3,4)
                     circle at (5,6)
                     box
                     .PE

              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
       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
              scale.

       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 lim‐
              ited 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
              following:

                     .PS
                     x = 3
                     y = 3
                     [
                       x := 5
                       y = 5
                     ]
                     print x " " y
                     .PE

              prints

                     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 }.

   Expressions
       The syntax for expressions has been significantly extended:

       x ^ y (exponentiation)
       sin(x)
       cos(x)
       atan2(y, x)
       log(x) (base 10)
       exp(x) (base 10, i.e. 10^x)
       sqrt(x)
       int(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)
       !e
       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 max‐
       psht.  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 rectan‐
       gle 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 verti‐
       cally 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 specified.

       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 tex‐
       twid; if the height attribute is not supplied then the height will be taken to be the num‐
       ber 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  sup‐
       plied.

       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 key‐
       words 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:

              .PS
              figname = foobar;
              ...
              .PE

       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
       units.

       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 box.se
              }

CONVERSION
       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®  for‐
       mat  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=

       Call

              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
       package .

FILES
       /usr/share/groff/1.22.3/tmac/pic.tmac   Example definitions of the PS and PE macros.

SEE ALSO
       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/pic.ps  (this  file,  together  with its source file, pic.ms, is
       part of the groff documentation)

       Tpic: Pic for TeX

       Brian W. Kernighan, PIC — A Graphics Language for Typesetting (User  Manual).   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 picMacros
       

BUGS
       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
       mode.

       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.

COPYING
       Copyright © 1989-2014 Free Software Foundation, Inc.

       Permission is granted to make and distribute verbatim copies of this manual  provided  the
       copyright notice and this permission notice are preserved on all copies.

       Permission  is  granted  to copy and distribute modified versions of this manual under the
       conditions for verbatim copying, provided that the entire resulting derived work  is  dis‐
       tributed under the terms of a permission notice identical to this one.

       Permission is granted to copy and distribute translations of this manual into another lan‐
       guage, under the above conditions for  modified  versions,  except  that  this  permission
       notice may be included in translations approved by the Free Software Foundation instead of
       in the original English.

Groff Version 1.22.3                     28 January 2016                                   PIC(1)

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