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pic - compile pictures for troff or TeX



        pic - compile pictures for troff or TeX


        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.
        The following options supported by other versions of pic are ignored:
        -D     Draw  all  lines  using the \D escape sequence.  pic always does
        -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
    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.
        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
                      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 con‐
               trol  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 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
        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 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.
        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) 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), 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  proportion‐
        ally  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:
               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 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® 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.
        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 .


        /usr/share/tmac/pic.tmac   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® is a registered trademark of Adobe Systems Incorporation.


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