Plotting a Simple Graph
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## Plotting a Simple Graph

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:

1. `plinit`, to initialize PLplot.

2. `plenv`, to define the range and scale of the graph, and draw labels, axes, etc.

3. 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.

4. `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.

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