327 lines
7.8 KiB
Plaintext
327 lines
7.8 KiB
Plaintext
.TH PIC 1
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.de PS \" start picture
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. \" $1 is height, $2 is width, both in inches
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.if \\$1>0 .sp .35
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.ie \\$1>0 .nr $1 \\$1
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.el .nr $1 0
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.in (\\n(.lu-\\$2)/2u
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.ne \\$1
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..
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.de PE \" end of picture
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.in
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.if \\n($1>0 .sp .65
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..
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.SH NAME
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pic \- troff preprocessor for drawing pictures
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.SH SYNOPSIS
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.B pic
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[
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.I files
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]
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.SH DESCRIPTION
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.I Pic
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is a
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.IR troff (1)
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preprocessor for drawing figures on a typesetter.
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.I Pic
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code is contained between
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.B .PS
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and
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.B .PE
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lines:
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.IP
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.EX
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\&.PS \f2optional-width\fP \f2optional-height\fP
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\f2element-list\fP
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\&.PE
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.EE
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.LP
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or in a file mentioned in a
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.B .PS
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line:
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.IP
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.BI .PS " " < file
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.LP
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If
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.IR optional-width
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is present, the picture is made that many inches wide,
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regardless of any dimensions used internally.
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The height is scaled in the same proportion unless
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.IR optional-height
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is present.
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If
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.B .PF
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is used instead of
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.BR .PE ,
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the typesetting position after printing is restored to what it was
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upon entry.
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.PP
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An
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.IR element-list
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is a list of elements:
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.EX
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\f2primitive attribute-list\fP
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\f2placename\fP : \f2element\fP
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\f2placename\fP : \f2position\fP
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\f2var\fP = \f2expr\fP
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\f2direction\fP
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{ \f2element-list\fP }
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[ \f2element-list\fP ]
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for \f2var\fP = \f2expr\fP to \f2expr\fP by \f2expr\fP do { \f2anything\fP }
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if \f2expr\fP then { \f2anything\fP } else { \f2anything\fP }
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copy \f2file,\fP copy thru \f2macro,\fP copy \f2file\fP thru \fPmacro\fP
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sh { \f2commandline\fP }
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print \f2expr\fP
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reset \f2optional var-list\fP
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\f2troff-command\fP
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.EE
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.PP
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Elements are separated by newlines or semicolons;
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a long element may be continued by ending the line with a backslash.
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Comments are introduced by a
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.BI #
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and terminated by a newline.
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Variable names begin with a lower case letter;
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place names begin with upper case.
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Place and variable names retain their values
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from one picture to the next.
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.PP
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After each primitive
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the current position moves in the current direction
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.RB ( up , down ,
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.BR left , right
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(default)) by the size of the primitive.
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The current position and direction are saved upon entry
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to a
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.BR { ... }
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block and restored upon exit.
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Elements within a block enclosed in
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.BR [ ... ]
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are treated as a unit;
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the dimensions are determined by the extreme points
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of the contained objects.
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Names, variables, and direction of motion within a block are local to that block.
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.PP
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.IR Troff-command
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is any line that begins with a period.
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Such a line is assumed to make sense in the context where it appears;
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generally, this means only size and font changes.
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.PP
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The
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.I primitive
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objects are:
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.br
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.EX
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box circle ellipse arc line arrow spline move \f2text-list\fP
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.EE
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.L arrow
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is a synonym for
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.LR "line ->" .
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.PP
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An
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.IR attribute-list
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is a sequence of zero or more attributes;
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each attribute consists of a keyword, perhaps followed by a value.
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.EX
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.ta .5i 2.5i
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h(eigh)t \f2expr\fP wid(th) \f2expr\fP
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rad(ius) \f2expr\fP diam(eter) \f2expr\fP
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up \f2opt-expr\fP down \f2opt-expr\fP
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right \f2opt-expr\fP left \f2opt-expr\fP
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from \f2position\fP to \f2position\fP
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at \f2position\fP with \f2corner\fP
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by \f2expr, expr\fP then
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dotted \f2opt-expr\fP dashed \f2opt-expr\fP
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chop \f2opt-expr\fP -> <- <->
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invis same
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fill \f2opt-expr\fP
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\f2text-list\fP \f2expr\fP
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.EE
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Missing attributes and values are filled in from defaults.
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Not all attributes make sense for all primitives;
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irrelevant ones are silently ignored.
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The attribute
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.L at
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causes the geometrical center to be put at the specified place;
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.L with
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causes the position on the object to be put at the specified place.
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For lines, splines and arcs,
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.L height
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and
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.L width
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refer to arrowhead size.
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A bare
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.I expr
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implies motion in the current direction.
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.PP
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Text is normally an attribute of some primitive;
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by default it is placed at the geometrical center of the object.
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Stand-alone text is also permitted.
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A text list
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is a list of text items:
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.EX
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\f2 text-item\fP:
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"..." \f2positioning ...\fP
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sprintf("\f2format\fP", \f2expr\fP, \f2...\fP) \f2positioning ...\fP
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\f2 positioning\fP:
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center ljust rjust above below
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.EE
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If there are multiple text items for some primitive,
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they are arranged vertically and centered except as qualified.
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Positioning requests apply to each item independently.
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Text items may contain
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.I troff
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commands for size and font changes, local motions, etc.,
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but make sure that these are balanced
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so that the entering state is restored before exiting.
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.PP
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A position is ultimately an
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.I x,y
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coordinate pair, but it may be specified in other ways.
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.EX
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\f2 position\fP:
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\f2expr, expr\fP
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\f2place\fP ± \f2expr, expr\fP
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\f2place\fP ± ( \f2expr, expr\fP )
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( \f2position\fP,\f2 position\fP ) \f2x\fP\fR from one, \f2y\fP\fR the other\fP
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\f2expr\fP [\fLof the way\fP] between \f2position\fP and \f2position\fP
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\f2expr\fP < \f2position\fP , \f2position\fP >
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( \f2position\fP )
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.EE
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.PP
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.EX
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\f2 place\fP:
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\f2placename\fP \f2optional-corner\fP
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\f2corner\fP of \f2placename\fP
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\f2nth\fP \f2primitive\fP \f2optional-corner\fP
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\f2corner\fP of \f2nth\fP \f2primitive\fP
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Here
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.EE
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An
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.IR optional-corner
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is one of the eight compass points
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or the center or the start or end of a primitive.
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.EX
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\f2 optional-corner\fP:
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.n .e .w .s .ne .se .nw .sw .c .start .end
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\f2 corner\fP:
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top bot left right start end
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.EE
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Each object in a picture has an ordinal number;
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.IR nth
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refers to this.
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.EX
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\f2 nth\fP:
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\f2n\fPth\f2, n\fPth last
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.EE
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.PP
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The built-in variables and their default values are:
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.EX
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.ta .5i 2.5i
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boxwid 0.75 boxht 0.5
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circlerad 0.25 arcrad 0.25
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ellipsewid 0.75 ellipseht 0.5
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linewid 0.5 lineht 0.5
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movewid 0.5 moveht 0.5
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textwid 0 textht 0
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arrowwid 0.05 arrowht 0.1
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dashwid 0.1 arrowhead 2
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scale 1
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.EE
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These may be changed at any time,
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and the new values remain in force from picture to picture until changed again
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or reset by a
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.L reset
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statement.
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Variables changed within
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.B [
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and
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.B ]
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revert to their previous value upon exit from the block.
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Dimensions are divided by
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.B scale
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during output.
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.PP
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Expressions in
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.I pic
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are evaluated in floating point.
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All numbers representing dimensions are taken to be in inches.
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.EX
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\f2 expr\fP:
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\f2expr\fP \f2op\fP \f2expr\fP
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- \f2expr\fP
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! \f2expr\fP
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( \f2expr\fP )
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variable
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number
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\f2place\fP .x \f2place\fP .y \f2place\fP .ht \f2place\fP .wid \f2place\fP .rad
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sin(\f2expr\fP) cos(\f2expr\fP) atan2(\f2expr,expr\fP) log(\f2expr\fP) exp(\f2expr\fP)
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sqrt(\f2expr\fP) max(\f2expr,expr\fP) min(\f2expr,expr\fP) int(\f2expr\fP) rand()
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\f2 op\fP:
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+ - * / % < <= > >= == != && ||
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.EE
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.PP
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The
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.B define
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and
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.B undef
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statements are not part of the grammar.
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.EX
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define \f2name\fP { \f2replacement text\fP }
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undef \f2name\fP
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.EE
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Occurrences of
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.BR $1 ,
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.BR $2 ,
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etc.,
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in the replacement text
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will be replaced by the corresponding arguments if
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.I name
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is invoked as
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.EX
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\f2name\fP(\f2arg1\fP, \f2arg2\fP, ...)
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.EE
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Non-existent arguments are replaced by null strings.
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Replacement text
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may contain newlines.
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The
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.B undef
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statement removes the definition of a macro.
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.SH EXAMPLES
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.EX
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arrow "input" above; box "process"; arrow "output" above
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move
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A: ellipse
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circle rad .1 with .w at A.e
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circle rad .05 at 0.5 <A.c, A.ne>
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circle rad .065 at 0.5 <A.c, A.ne>
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spline from last circle.nw left .25 then left .05 down .05
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arc from A.c to A.se rad 0.5
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for i = 1 to 10 do { line from A.s+.025*i,.01*i down i/50 }
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.EE
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.PP
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.PS
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arrow "input" above; box "process"; arrow "output" above
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move
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A: ellipse
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circle rad .1 with .w at A.e
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circle rad .05 at 0.5 <A.c, A.ne>
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circle rad .065 at 0.5 <A.c, A.ne>
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spline from last circle.nw left .25 then left .05 down .05
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arc from A.c to A.se rad 0.5
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for i = 1 to 10 do { line from A.s+.025*i,.01*i down i/50 }
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.PE
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.SH SOURCE
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.B /sys/src/cmd/pic
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.SH "SEE ALSO"
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.IR grap (1),
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.IR doctype (1),
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.IR troff (1)
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.br
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B. W. Kernighan,
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``PIC\(ema Graphics Language for Typesetting'',
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.I
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Unix Research System Programmer's Manual,
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Tenth Edition, Volume 2
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