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Plotting library

The graphics.cpl library provides basic plotting instructions by linking a CPL program to GNU plotutils. The same programming interface is also shared by nographics and gnuplot

Menu:

OPENGRAPH:	start a new graph
MOUSEGRAPH:	start a new graph with mouse grabbing capability
WINDOW:	specify a drawing window within the current graph
RANGE:	specify a range for the axes
STARTLINE:	start a new line
DRAW:	draw a line segment
LABEL:	add a text label
SHOWGRAPH:	flush the current graph on screen
PLOT:	plot a complete curve with default settings
strlines:	Streamline plotting

Page: (graphics)OPENGRAPH, Next: WINDOW, Prev: Top, Up: Top Index

SUBROUTINE OPENGRAPH()

SUBROUTINE OPENGRAPH(STRING filename)

SUBROUTINE OPENGRAPH(INTEGER n)

Starts a new graph, or clears a previously existing one. If the argument <filename> is specified, the graph is simultaneously piped to the screen and to a file of graphics commands that allows the graph to be reproduced later. If the argument <n> is specified (available in the gnuplot version only) a new window numbered <n> is opened and the previous graph window is left on screen. Most graphics commands invoke OPENGRAPH() automatically if no graph was previously opened.

SUBROUTINE CLOSEGRAPH()

closes a graphics window (not necessary when opening a new one).

Page: (graphics)MOUSEGRAPH, Next: WINDOW, Prev: OPENGRAPH, Up: Top Index

SUBROUTINE MOUSEGRAPH()

starts a new graph with mouse grabbing capability,

SUBROUTINE POLLMOUSE(REAL mx^,my^; INTEGER mb^)

grabs mouse clicks in gnuplot window.

Page: (graphics)WINDOW, Next: RANGE, Prev: MOUSEGRAPH, Up: Top Index

SUBROUTINE WINDOW(REAL VARIABLE x1, x2, y1, y2)

specifies a plotting window within the current graph, in a system of coordinates going from 0 to 1 along either axis. If WINDOW was not specified, 0,1,0,1 is assumed.

Page: (graphics)RANGE, Next: STARTLINE, Prev: WINDOW, Up: Top Index

SUBROUTINE RANGE(REAL x1,x2; FUNCTION(REAL z)->REAL newxmap; REAL y1,y2; FUNCTION(REAL z)->REAL newymap)

SUBROUTINE RANGE(REAL x1,x2,y1,y2)

specify a range for the drawing coordinates on either axis, and possibly a mapping function (system- or user-provided). For example: RANGE(0,100,-1,2.5) RANGE(1,100,LOG,0,10,LIN) The predefined function LIN provides a linear identity mapping. The current range may be read from the REAL CONSTANT XMIN,XMAX,YMIN,YMAX If RANGE was not specified, 0,1,0,1 is assumed (except for PLOT).

Page: (graphics)STARTLINE, Next: DRAW, Prev: RANGE, Up: Top Index

SUBROUTINE STARTLINE()

SUBROUTINE STARTCIRCLE()

SUBROUTINE STARTLINE(ARRAY(∗) OF CHAR style)

Starts a new line (chain of segments) within the current graph. That is, the next DRAW command will not draw a segment but just a point. STARTCIRCLE specifies that a small circle be drawn in each point rather than connecting them with segments. In the gnuplot version only, the argument <style> may be added to specify a gnuplot-recognized line style.

Page: (graphics)DRAW, Next: LABEL, Prev: STARTLINE, Up: Top Index

SUBROUTINE DRAW(REAL x,y)

The basic drawing primitive, draws a line segment up to point <x>, <y> or a symbol according to the style specified by STARTLINE.

SUBROUTINE MOVE(REAL x,y)

is equivalent to STARTLINE; DRAW x,y

SUBROUTINE LINE(REAL x1,y1,x2,y2)

is equivalent to STARTLINE; DRAW x1,y1; DRAW x2,y2

SUBROUTINE BOX(REAL x1,x2,y1,y2)

SUBROUTINE CIRCLE(REAL x,y,r)

do what their names imply.

Page: (graphics)LABEL, Next: SHOWGRAPH, Prev: DRAW, Up: Top Index

SUBROUTINE LABEL(REAL x,y; POINTER TO CSTRING s)

writes character string <s> starting at coordinates <x>, <y>.

Page: (graphics)SHOWGRAPH, Next: PLOT, Prev: LABEL, Up: Top Index

SUBROUTINE SHOWGRAPH()

flushes the internal buffer, which could otherwise delay the graph from being shown on screen.

Page: (graphics)PLOT, Next: nographics, Prev: SHOWGRAPH, Up: Top Index

SUBROUTINE PLOT(REAL FUNCTION(INTEGER n) fy; INTEGER x1..x2)

plot real function over an interval of integers

SUBROUTINE PLOT(REAL FUNCTION(INTEGER n) fy,fx; INTEGER x1..x2)

plot first versus second function over an array of points

SUBROUTINE PLOT(REAL FUNCTION(INTEGER n) fy; ARRAY(∗) OF REAL vecx)

plot real function over an array of points

SUBROUTINE PLOT(REAL FUNCTION(REAL x) f; REAL x1..x2)

plot real function over real interval

SUBROUTINE PLOT(REAL FUNCTION(REAL x) f)

plot real function over preset interval

SUBROUTINE PLOT(ARRAY(∗) OF REAL vec)

plot real array versus its index

SUBROUTINE PLOT(ARRAY(∗) OF INTEGER vec)

plot integer array versus its index

SUBROUTINE PLOT(ARRAY(∗) OF REAL vecy,vecx)

plot first versus second array

SUBROUTINE PLOT(ARRAY(∗) OF REAL vecy; ARRAY(∗) OF INTEGER vecx)

plot first versus second array These subroutines have the purpose of plotting a function or data array in a predefined format with a single command. If a RANGE was not specified between OPENGRAPH and the current PLOT, it is automatically determined. As a more flexible alternative the plot command is also available which more directly mimics, and offers all the options of, gnuplot's plot.

Page: (graphics)nographics, Next: gnuplot, Prev: Top, Up: Top Index

nographics.cpl

Fake plotting package that allows graphics to be turned off by USEing this library instead of graphics without modifying the rest of the program.

Page: (graphics)gnuplot, Next: strlines, Prev: nographics, Up: Top Index

gnuplot.cpl

This library provides the same plotting instructions as graphics.cpl but pipes the appropriate commands to a gnuplot process. In addition the following commands are available in gnuplot.cpl only:

Menu:

set:	gnuplot set. Passed to gnuplot as is.
plot:	gnuplot plot. Accepts CPL ARRAYS and FUNCTIONS and transparently
passes them to gnuplot using gnuplot syntax. Example:
plot x:SIN[x(n)] w l, where x is an ARRAY OF REAL.
SPLOT:	plot a surface with default settings
REALTABLE(POINTER TO FILE): reads a matrix of REALs from a file in table
format, with automatic dimensioning.
WRITE TABLE [TO POINTER TO FILE]: accepts the same syntax as plot, but
writes out the corresponding data in table format.
OPENMOVIE <filename>: pipes the output of gnuplot to ffmpeg and the output
of ffmpeg to <filename>, in such a way that a movie is produced from
whatever graphic commands follow.

Page: (graphics)SPLOT, Next: strlines, Prev: gnuplot, Up: gnuplot Index

SUBROUTINE SPLOT(REAL FUNCTION(REAL x,y) f; REAL xmin..xmax,ymin..ymax)

SUBROUTINE SPLOT(REAL FUNCTION(REAL x,y) f)

SUBROUTINE SPLOT(REAL FUNCTION(INTEGER x,y) vec; INTEGER xmin..xmax,ymin..ymax)

SUBROUTINE SPLOT(REAL FUNCTION(INTEGER x,y) vec; ARRAY(∗) OF REAL x,y)

SUBROUTINE SPLOT(ARRAY(∗,∗) OF REAL vec)

SUBROUTINE SPLOT(ARRAY(∗,∗) OF INTEGER vec)

SUBROUTINE SPLOT(ARRAY(∗,∗) OF REAL vec; ARRAY(∗) OF REAL x,y)

Page: (graphics)strlines, Next: (parallel), Prev: gnuplot, Up: Top Index

strlines.cpl

SUBROUTINE ShowStr[INTEGER n; ARRAY(∗,∗) OF REAL umat,vmat]

draws n randomly positioned streamline segments out of u and v staggered velocity components.

SUBROUTINE ShowStr[INTEGER n; ARRAY(∗,∗) OF REAL umat,vmat; REAL FUNCTION(INTEGER i) xr,yr]

adds the specification of possibly non-uniform x and y coordinates.