| 
        This is starting to look more and more like a physical set of voltages.  
        Each iteration changes the values in the matrix less and less as the 
        solution asymptotically converges to the physical solution. In fact, 
        this iteration process could continue indefinitely.  We must have a
        stopping criterion, which is basically a test to detect whether 
        or not we've reached the right answer.  The simplest stopping 
        criteria are based on the maximum changes in voltages from iteration to 
        iteration.  If the values in the matrix are changing very slightly, 
        we have likely reached the solution.  |