Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: visualizing fields near charged objects

At 11:56 AM 2/9/01 -0800, Leigh Palmer wrote:
Denker seems to believe that total charge should be constant
during iteration. Have you any reason to believe that should be

I have the following reason:

b w c

Consider a grid (called the potential grid) containing zeros on the two
rows or columns nearest each edge, and arbitrary values in the interior.
Now convolve that with the operator (a+b+c+d)-4w to form the charge grid.
Every nonzero potential cell contributes to the convolution grid five
times: once as a, once as b, once as c, once as d, and once (weighted by
-4) as w. If you add those five contributions, you get zero every time.
*) A small discrepancy might be attributable to roundoff errors.
*) A large discrepancy cannot have a good reason. Non-good reasons include
-- serious bugs in the algorithm or the implementation
-- perhaps not summing the charge over
all places where charge might be found.

Does that answer the question?