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PIC(1)                                                                                                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), appro-priate appropriate
       priate definitions can be obtained with -mpic: These will center 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 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  pre-vious previous
              vious  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 gener-ated generated
              ated 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 documentation is available in
       the file

              /usr/share/doc/groff/1.19.2/pic.ms

   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

              \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 \base-lineskip. \baselineskip.
       lineskip.  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 charac-ter character
              ter 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-delim-ited blank-delimited
              ited  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,

                     .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 limited checking of the string.  This is  depre-cated deprecated
              cated 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  imbal-anced imbalanced
       anced 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, ie 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 maxpsht.  Ini-
       tially 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.

       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 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 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 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  pro-portional proportional
       portional to the pointsize.  A zero value means draw the thinnest possible line supported by the out-put output
       put 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), 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 spec-ifying specifying
       ifying 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 spe-cially specially
       cially 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.  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  num-ber, number,
       ber,  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(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 PostScript interpreter ghostscript (gs) has built-in graphics conversion devices that are  called
       with the option

              gs -sDEVICE=<devname>

       Call

              gs --help

       for a list of the available devices.

       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/1.19.2/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)

       Tpic: Pic for TeX

       Brian W. Kernighan, PIC -- A Graphics Language for Typesetting (User Manual).   AT&T  Bell  Laborato-ries, Laboratories,
       ries,  Computing  Science  Technical  Report  No. 116  <http://cm.bell-labs.com/cm/cs/cstr/116.ps.gz>
       (revised May, 1991).

       ps2eps is available from CTAN mirrors, e.g.
       <ftp://ftp.dante.de/tex-archive/support/ps2eps/>

       W. Richard Stevens - Turning PIC Into HTML
       <http://www.kohala.com/start/troff/pic2html.html>

       W. Richard Stevens - Examples of picMacros
       <http://www.kohala.com/start/troff/pic.examples.ps>

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



Groff Version 1.19.2                            19 July 2004                                          PIC(1)

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