On 22 April 2010 09:59, Bo Jacoby <[email protected]> wrote: > Boyko Bantchev wrote: "The winding number method ... is computationally awful > and for this reason not much used." > > Nobody really knows how much it is used, I guess.
If you mean a precise number of uses or users, then yes, ‘nobody really knows’. But do google for "worst algorithm in the world for testing points" and see who the champion is. > I find the winding number formula > W=.(%&0j2p1)@(+/)@:^.@(% _1&|.) > short and simple and computationally quite OK. > It is, (divided by 2 pi i), the sum of the logarithm > of the quotients between each corner and its predecessor. Angles? Quotients? Even logarithms? How is this simpler and more robust than only using addition and multiplication? Specifically, why should one, given integer coordinates, use complicated floating-point calculations to obtain the result? That would be both prone to errors and less efficient. ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
