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PIC(1)			    General Commands Manual			PIC(1)

       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 be-
	      ginning with .ps is given	special	treatment:  it	takes  an  op-
	      tional 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-nega-
	      tive  line thickness has not been	specified by use of the	thick-
	      ness 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 ex-
       ample, 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.	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.

       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-de-
	      fined 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

	      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	}.

       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 legal.

       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 and arcs	can be dotted or dashed.  In TeX mode splines  can  be
       dotted or dashed.

       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 ig-
       nored 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 mo-
       tion 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  ob-
       ject times textht.  Initially textwid and textht	have a value of	0.

       In  (almost  all) places	where a	quoted text string can be used,	an ex-
       pression	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 op-
       tional 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; ad-
       ditional	colors can be defined with the .defcolor request (see the man-
       ual 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 ar-
       row 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

       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 (ie 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 1.19		 26 June 2003				PIC(1)


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