Visualizing Functions of 2 Variables parameterized over arbitrary regions

Description

see_function (a, n, b, c) is a maple procedure that takes a function (expression) in two variables and evaluates the 2-d function over some region specified by the 2nd and 3rd arguments. It then rounds the values of the function at the lattice points in the region to the nearest integer and reduces these integers modulo 10 by default (4th argument) and displays them in the region specified by the 2nd and 3rd arguments.

Note, that the region specified by the 2nd and 3rd arguments are not restricted to rectangles. For example, a triangular region could be specified by setting the 2nd argument to i=0..20 and the 3rd argument to j=0..i. Another example would be a circular region defined by 2nd argument by i = -sqrt(25^2 - j^2)..+sqrt(25^2 - j^2) and the 3rd argument by j = -25..25. Another examples is the triangular region defined by i=0..30, j=0..i.