Graph Plotter: Plot graphics of a given function expression

This class can be used to plot a graphic of a function given its expression.
*** This class requires EvalMath by Miles Kaufmann http://www.phpclasses.org/evalmath for better expression evaluation before plotting. ***

It can evaluate the given function for a given interval of x and y variable values and draw lines between the calculated points.

The class also draws a grid of scale values as well the X and Y axis.

More than one graphic can be rendered in the same image. The resulting image is outputted in the PNG format.