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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.

   TeX mode
       TeX mode	is enabled by the -t option.  In TeX mode, pic will  define  a
       vbox called \graph for each picture.  You must yourself print that vbox
       using, for example, the command


       Actually, since the vbox	 has  a	 height	 of  zero  this	 will  produce
       slightly	more vertical space above the picture than below it;

	      \centerline{\raise 1em\box\graph}

       would avoid this.

       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  orTeX.   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.

	      This is similar to = except variable must	 already  be  defined,
	      and  the value of	variable will be changed only in the innermost
	      block in which it	is defined.  (By contrast, = defines the vari-
	      able  in	the  current block if it is not	already	defined	there,
	      and then changes the value in the	current	block.)

       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 10x)
       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  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 hori-
       zontally.  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  places where	a quoted text string can be used, an expression	of the

	      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, using only the	e, f, g	 or  %
       format characters.

       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 then	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.

       Arrow heads will	be drawn as solid triangles if the variable  arrowhead
       is  non-zero  and  either TeX mode is enabled or	the -x option has been
       given.  Initially arrowhead has a value of 1.

       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  when  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	 <URL:>   (revised
       May, 1991).

       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 illegal for groff (ie those with ASCII	code 0
       or between 013 and 037 octal or between 0200 and	0237  octal)  are  re-
       jected 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 1.17.2		 6 August 2001				PIC(1)


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