http://dsh.cs.washington.edu:8000/Projects/04s126/upload/040222-080543.cgi-lib.16420.1.Laplace2.jpeg

P.S. Again, the code calculates equipotentials for a given fixed potential of 0 on the outer square and 100 on the inner by diving the area to be considered into a finite number of points. In each iteration, it takes for the new potential value at a given point the average of the surrounding 4 potential values (right,left,above,below).  



Randy