We shall first consider plotting simple graphs showing the dependence
of one variable upon another. Such a graph may be composed of several
elements:
- A box which defines the ranges of the variables, perhaps with axes
and numeric labels along its edges,
- A set of points or lines within the box showing the functional
dependence,
- A set of labels for the variables and a title for the graph.
In order to draw such a graph, it is necessary to call at least four of
the PLPLOT functions:
- plstar, to specify the device you want to plot on,
- plenv, to define the range and scale of the graph, and
draw labels, axes, etc.,
- One or more calls to plline or plpoin to draw
lines or points as needed. Other more complex routines include
plbin and plhist to draw histograms, plerrx and
plerry to draw error-bars,
- plend, to close the plot.
More than one graph can be drawn on a single set of axes by making
repeated calls to the routines listed in item ![[*]](crossref.png)
above. The routine
plstar needs to be called only once, unless a different output device
is required.