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

       This manual page describes the GNU version of pic, which is part of the
       groff document formatting system.  pic compiles  descriptions  of  pic-
       tures  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 sup-
       ply 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 input.

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

       -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.



   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 docu-

                 \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  treat-

       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.

                     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
              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 vari-
              able 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:

                     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, ie 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

   Other Changes
       A  bare  expression, expr, is acceptable as an attribute; it is equiva-
       lent 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  vari-
       ables 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

              [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
       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) appropri-
       ate for the number of arguments supplied.

       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 sup-
       ported 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 pic-
       ture.  Example:

       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 there-
       fore  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.  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

              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 trans-
       form your picture into PostScript(R)  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 Post-
       Script interpreter ghostscript (gs) has  built-in  graphics  conversion
       devices that are called with the option

              gs -sDEVICE=<devname>


              gs --help

              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)

       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,

       ps2eps is available from CTAN mirrors, e.g.

       W. Richard Stevens - Turning PIC Into HTML

       W. Richard Stevens - Examples of picMacros

       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 edi-
       tion Unix, which interprets 0 as black and 1 as white.

       PostScript(R) is a registered trademark of Adobe Systems Incorporation.

Groff Version 1.21               01 April 2012                          PIC(1)
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