Re: Re: point in convex hull

*To*: mathgroup at smc.vnet.net*Subject*: [mg55487] Re: [mg55477] Re: point in convex hull*From*: DrBob <drbob at bigfoot.com>*Date*: Sat, 26 Mar 2005 02:39:19 -0500 (EST)*References*: <d1tvc0$rli$1@smc.vnet.net> <200503251048.FAA11334@smc.vnet.net>*Reply-to*: drbob at bigfoot.com*Sender*: owner-wri-mathgroup at wolfram.com

If w is one of the points in ch, ConvexHull throws a message, so I'd suggest this: inside[w_, ch_] := MemberQ[ch, w] || ! MemberQ[ConvexHull@Append[ch, w], 1 + Length@ch] Bobby On Fri, 25 Mar 2005 05:48:18 -0500 (EST), Carl K. Woll <carlw at u.washington.edu> wrote: > "steve fisk" <fisk at bowdoin.edu> wrote in message > news:d1tvc0$rli$1 at smc.vnet.net... >> If pts is a set of points, and w is a point I can use ConvexHull[pts] to >> find the convex hull of the points in pts. Is there a function to >> determine if w lies in the convex hull? >> > > Steve, > > Why don't you find out if the ConvexHull of w added to the old ConvexHull > includes the point w. Something like > > Needs["DiscreteMath`"] > > pts=Table[{Random[],Random[]},{1000}]; > ch=pts[[ConvexHull[pts]]]; > > inside[w_, ch_] := ! MemberQ[ConvexHull[Join[ch, {w}]], Length[ch] + 1] > > Carl Woll > > > > > > -- DrBob at bigfoot.com

**References**:**Re: point in convex hull***From:*"Carl K. Woll" <carlw@u.washington.edu>