----- Original Message ---- From: Steve Witham <sw@tiac.net> To: math-fun@mailman.xmission.com Sent: Saturday, December 15, 2007 3:32:41 PM Subject: [math-fun] xkcd points out dangers of math fun Here's a comic with an interesting random-walk problem: http://www.xkcd.com/356/ --Steve _______________________________________________ On a square grid of 1 ohm resistors, the effective resistance between the node at (0,0) and the node at (p,q) is given by the following expression. R[p,q] = (1/(4 pi^2)) int (F(x,y), x=-pi..pi, y=-pi..pi), F(x,y) = [1 - cos(p x + q y)] / [2 - (cos x + cos y)]. Gene ____________________________________________________________________________________ Never miss a thing. Make Yahoo your home page. http://www.yahoo.com/r/hs