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.
A graphics window may be closed without opening a new one by the
specify a range for the drawing coordinates on either axis, and possibly a mapping function (system- or user-provided). For example:
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).
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.
SUBROUTINE PLOT(REAL FUNCTION(INTEGER) f; ARRAY(∗) OF REAL vecx)
SUBROUTINE PLOT(ARRAY(∗) OF REAL vec)
SUBROUTINE PLOT(ARRAY(∗) OF REAL vecy,vecx)
These subroutines have the purpose of plotting an entire 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.