3.5 The Graphing Library

The (plotutils graph) library is mostly the graph procedure, a single procedure with dozens of options

Procedure: graph ylist
Procedure: graph xlist ylist
Procedure: graph yproc xstart xend
Procedure: graph yproc xstart xend xstep

graph can take up to four arguments.

To plot sampled data, graph is called either with one list or two lists of floating point data. When called with one list, the abscissa will be created automatically. When called with two lists, they must be equal length with one being the x-data and the other being the y-data.

To plot more than one set of sampled data on a plot, two lists can be joined using the merge procedure.

(graph (merge xlist1 xlist2) (merge ylist1 ylist2))

To plot a single-valued function – a procedure that takes one numeric argument and returns one numeric argument – graph can be called with a procedure and two or three arguments that define the x-range of the abcissa. When called with xstart and xend but not xstep a default number of samples will be computed from the procedure: a few hundred points. When xstep is included, it will be the step size of the samples.

There are a couple dozen optional parameters.