Plotting inequalities (ineqplot)

Plotting inequalities, simple and easy.
Syntax:

h = ineqplot(I, R, c);

Input arguments
I - Inequality as string, i.e. 'x+y>10'
R - Vector of four components defined by: [xmin, xmax, ymin, ymax],
if two components are passed: [min, max], the defined region
will be a square and xmin=ymin=min, xmax=ymax=max.
c - A three-element RGB vector, or one of the MATLAB
predefined names, specifying the plot color.

Output arguments
h - returns the handle of the scattergroup
object created.

Examples:
>> ineqplot('x.^2+y.^2<10',[-5 5], 'r');
>> h = ineqplot('y<x+3',[0 10 -5 5]);
>> set(h,'MarkerFaceColor','r'); % Change color