You might check out the Rosetta code task http://rosettacode.org/wiki/Resistor_mesh
that has a link to this problem. The Maxima solution has an explanation included.
On 07-01-13 23:36, Raul Miller wrote:
http://xkcd.com/356/ proposes a problem involving finding the resistance in a case involving an infinite number of resistors. Before I can reason about that graph, I'd want a systematic way of reasoning about much more trivial cases. So... here's a representation of a square with four corners: Resistors connect corner 0 with corner 1, corner 1 with corner 2, and both corners 1 and 2 with corner 3. Unnamed corner pairs are not connected. All resistors are 1 ohm. The expected net resistance between corner 0 and corner 3 should be 1 ohm. 1 ((, |.&.>)0 1;0 2;1 3;2 3)} <:%=i. 4 0 1 1 _ 1 0 _ 1 1 _ 0 1 _ 1 1 0 The values in this table represent the resistor connecting the two corners whose row/column indices represent the locations in the network. But.. how would I express this calculation without encoding the grid into the calculation itself? (In other words, so that any such resistance graph is allowed -- though it is ok to assume that the matrix describing the connections is symmetric.) This is probably fairly trivial for anyone with an EE background, but I'm not quite seeing how to approach this. Thanks,
-- Met vriendelijke groet, @@i = Arie Groeneveld ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
