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.TH PLOT 6

.SH NAME

plot \- graphics interface

.SH DESCRIPTION

Files of this format are interpreted by

.IR  plot (1)

to draw graphics on the screen.

A

.I plot

file is a

.SM UTF

stream of

instruction lines.

Arguments are delimited by spaces, tabs, or commas.

Numbers may be floating point.

Punctuation marks (except 

.LR : )

,

spaces, and tabs at the beginning of lines are ignored.

Comments run from  

.L :

to newline.

Extra letters appended to a valid instruction are ignored.

Thus

.LR ...line ,

.LR line , and 

.L li

all mean the same thing.

Arguments are interpreted as follows:

.TP

1.

If an instruction requires no arguments, the rest of the line is ignored.

.TP

2.

If it requires a string argument, then all the line

after the first field separator is passed as argument.

Quote marks may be used to preserve leading blanks.

Strings may include newlines represented as

.LR \en .

.TP

3.

Between numeric arguments alphabetic characters and

punctuation marks are ignored.

Thus

.L

line from 5 6 to 7 8

draws a line from (5, 6) to (7, 8).

.TP

4.

Instructions with numeric arguments remain in effect until

a new instruction is read.

Such commands may spill over many lines. Thus

the following sequence will draw a polygon

with vertices

(4.5, 6.77), (5.8, 5.6), (7.8, 4.55), and (10.0, 3.6).

.IP

.EX

move 4.5 6.77

vec 5.8, 5.6 7.8

4.55 10.0, 3.6 4.5, 6.77

.EE

.PP

The instructions are executed in order.

The last designated point in a

.BR line ", " move ", " rmove ,

.BR vec ", " rvec ", " arc ,

or

.B point

command becomes the `current point'

.RI ( X,Y )

for the next command.

.SS "Open & Close"

.PD0

.TP 10

.BI o " string"

Open plotting device.

For 

.IR troff ,

.I string

specifies the size of the plot

(default is

.LR 6i ).

.TP 10

.B cl

Close plotting device.

.PD

.SS "Basic Plotting Commands"

.PD0

.TP 10

.B e

Start another frame of output.

.TP 10

.BI m " x y"

(move) Current point becomes

.I "x y."

.TP 10

.BI rm " dx dy"

Current point becomes

.I "X+dx Y+dy."

.TP 10

.BI poi " x y"

Plot the point

.I "x y"

and make it the current point.

.TP 10

.BI v " x y"

Draw a vector from the current point to

.I "x y."

.TP 10

.BI rv " dx dy"

Draw vector from current point to

.RI X + dx

.RI Y + dy

.TP 10

.BI li " x1 y1 x2 y2"

Draw a line from

.I "x1 y1"

to

.I "x2 y2."

Make the current point

.I "x2 y2."

.TP 10

.BI t " string"

Place the

.I string

so that its

first character is centered on the current point (default).

If

.I string

begins with

.L \eC

.RL ( \eR ),

it is centered (right-adjusted) on the current point.

A backslash at the beginning of the string may

be escaped with another backslash.

.TP 10

.BI a " x1 y1 x2 y2 xc yc r"

Draw a circular arc from

.I "x1 y1"

to

.I "x2 y2"

with center

.I "xc yc"

and radius

.IR r .

If the radius is positive, the arc is drawn counterclockwise;

negative, clockwise.

The starting point is exact but the ending point is approximate.

.TP 10

.BI ci " xc yc r"

Draw a circle centered at

.I "xc yc"

with radius

.IR r .

If the range and frame parameters do not specify a square,

the `circle' will be elliptical.

.TP 10

.BI di " xc yc r"

Draw a disc centered at

.I "xc yc"

with radius

.I r

using the filling color (see 

.B cfill

below).

.TP 10

.BI bo " x1 y1 x2 y2"

Draw a box with lower left corner at

.I "x1 y1"

and upper right corner at

.I "x2 y2."

.TP 10

.BI sb " x1 y1 x2 y2"

Draw a solid box with lower left corner at

.I "x1 y1"

and upper right corner at

.I "x2 y2"

using the filling color (see 

.B cfill

below).

.TP 10

.BI par " x1 y1 x2 y2 xg yg"

Draw a parabola from

.I "x1 y1"

to

.I "x2 y2"

`guided' by

.I "xg yg."

The parabola passes through the midpoint of the line joining

.I "xg yg"

with the midpoint of the line

joining

.I "x1 y1"

and

.I "x2 y2"

and is tangent to the lines from

.I "xg yg"

to the endpoints.

.TP 10

.BI "pol { {" "x1 y1 ... xn yn" } " ... " { "X1 Y1 ... Xm Ym\fP} }\fI"

Draw polygons with vertices

.I "x1 y1 ... xn yn"

and

.I "X1 Y1 ... Xm Ym."

If only one polygon is specified, the inner brackets are

not needed.

.TP 10

.BI "fi { {" "x1 y1 ... xn yn" } " ... " { "X1 Y1 ... Xm Ym\fP} }\fI"

Fill a polygon.

The arguments are the same as those for

.B pol

except that the first vertex is automatically repeated to

close each polygon.

The polygons do not have to be connected.

Enclosed polygons appear as holes.

.TP 10

.BI "sp { {" "x1 y1 ... xn yn" } " ... " { "X1 Y1 ... Xm Ym\fL} }\fI"

Draw a parabolic spline guided by

.I "x1 y1 ... xn yn"

with simple endpoints.

.TP 10

.BI "fsp { {" "x1 y1 ... xn yn" } " ... " { "X1 Y1 ... Xm Ym\fL} }\fI"

Draw a parabolic spline guided by

.I "x1 y1 ... xn yn"

with double first endpoint.

.TP 10

.BI "lsp { {" "x1 y1 ... xn yn" } " ... " { "X1 Y1 ... Xm Ym\fL} }\fI"

Draw a parabolic spline guided by

.I "x1 y1 ... xn yn"

with double last endpoint.

.TP 10

.BI "dsp { {" "x1 y1 ... xn yn" } " ... " { "X1 Y1 ... Xm Ym\fL} }\fI"

Draw a parabolic spline guided by

.I "x1 y1 ... xn yn"

with double endpoints.

.TP 10

.BI "csp { {" "x1 y1 ... xn yn" } " ... " { "X1 Y1 ... Xm Ym\fL} }\fI"

.TP 10

.BI in " filename"

(include) Take commands from

.IR filename .

.TP 10

.BI de " string " { " commands " }

Define

.I string

as

.IR commands .

.TP 10

.BI ca " string scale"

Invoke commands defined as

.I string

applying

.I scale

to all coordinates.

.PD

.SS "Commands Controlling the Environment"

.PD0

.TP 10

.BI co " string"

Use color given by first character of

.IR string ,

one of

.BR red ,

.BR yellow ,

.BR green ,

.BR blue ,

.BR cyan ,

.BR magenta ,

.BR white ,

and

.BR kblack .

.TP 10

.BI pe " string"

Use

.I string

as the style for drawing lines.

The available pen styles are:

.BR solid ,

.BR  dott [ed],

.BR short ,

.BR long ,

.BR dotd [ashed] ,

.BR cdash ,

.BR ddash

.TP 10

.BI cf " string"

Color for filling (see

.BR co ,

above).

.TP 10

.BI ra " x1 y1 x2 y2"

The data will fall between

.I "x1 y1"

and

.I "x2 y2."

The plot will be magnified or reduced to fit

the device as closely as possible.

.IP

Range settings that exactly fill the plotting area

with unity scaling appear below for

devices supported by the filters of

.IR  plot (1).

The upper limit is just outside the plotting area.

In every case the plotting area is taken to be square;

points outside may be displayable on

devices with nonsquare faces.

.TP 10

.BI fr " px1 py1 px2 py2"

Plot the data in the fraction of the display

specified by

.I "px1 py1"

for lower left corner

and

.I "px2 py2"

for upper right corner.

Thus  

.L frame .5 0 1. .5

plots in the lower right

quadrant of the display;

.L frame 0. 1. 1. 0.

uses the whole display but

inverts the

.I y

coordinates.

.TP 10

.B sa

Save the current environment, and move to a new one.

The new environment inherits the old one.

There are 7 levels.

.TP 10

.B re

Restore previous environment.

.PD

.SH "SEE ALSO"

.IR plot (1), 

.IR graph (1)