Devon McCormick wrote: > it will be interesting to > see how the winding number algorithm performs on actual > data.
Thanks to Devon for that constructive remark. Here are some test runs. W=.%&0j2p1@(+/)@:^.@(% _1&|.) NB. Winding number program R=.<.@(0.5&+)@(9&o.) NB. Rounding a complex number into an integer C=.$~>:@$ NB. Closing a polygon RP=._1&^...@+:@(%~i.) NB. Regular Polygon TP=.(, 0.5&*@|.)4*RP 6 NB. Test Polygon plot C TP NB. show the closed test polygon r...@w TP NB. Rounded Winding number around 0j0 of Test Polygon 0 NB. Correct result. 0j0 is outside the polygon r...@w TP-/2 3 NB. vertex 2j0 and edge point 3j0 0 0 NB. Acceptable result r...@w TP-/i.6 0 0 0 0 0 0 NB. Correct result. r...@w TP-/j.i.6 0 0 1 1 0 0 NB. Correct result. r...@w TP-/-i.6. 0 0 1 1 0 0 NB. Correct result r...@w (-/])TP 0 1 0 0 0 0 1 1 1 1 0 0 NB. Some vertices are considered inside, others outside Summary: The winding number program performs satisfactory. -Bo --- Den fre 23/4/10 skrev Devon McCormick <[email protected]>: > Fra: Devon McCormick <[email protected]> > Emne: Re: [Jprogramming] Polygon containment > Til: "Programming forum" <[email protected]> > Dato: fredag 23. april 2010 01.39 > All these good theoretical > considerations aside, it will be interesting to > see how the winding number algorithm performs on actual > data. > > On Thu, Apr 22, 2010 at 6:52 PM, Boyko Bantchev <[email protected]> > wrote: > > > On 23 April 2010 00:02, Bo Jacoby <[email protected]> > wrote: > > > The winding number program > (%&0j2p1)@(+/)@:^.@(% _1&|.) is not "slow, > > unstable, and incomplete (hence buggy)". > > > > Of course it is. It does not handle boundary > cases. It uses too > > complicated operations, introducing inaccuracy and > unstability > > where it – by the nature of the problem – should > absolutely not. > > That same operations make it slow, too. > > > ... > > -- > Devon McCormick, CFA > ^me^ at acm. > org is my > preferred e-mail > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
