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.
For a good tutorial example of such a simple graph for each of our supported languages, see our standard example 00.
In order to draw such a simple graph, it is necessary to call at least four of the PLplot functions:
	  plinit, to initialize PLplot.
	
	  plenv, to define the range and scale of the
	  graph, and draw labels, axes, etc.
	
	  One or more calls to plline or plstring to draw lines or points
	  as needed.  Other more complex routines include plbin and
	  plhist to draw histograms, and 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 3 above. PLplot only needs to be initialized once unless plotting to multiple output devices.