Re: extracting points and projecting

*To*: mathgroup at smc.vnet.net*Subject*: [mg98114] Re: extracting points and projecting*From*: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>*Date*: Mon, 30 Mar 2009 05:19:50 -0500 (EST)*Organization*: Uni Leipzig*References*: <gqq3s0$7ml$1@smc.vnet.net>*Reply-to*: kuska at informatik.uni-leipzig.de

Hi, g = ContourPlot[Arg[Gamma[x + I*y]] == 0, {x, -10, 10}, {y, -10, 10}, PlotPoints -> 100]; j1[x_, y_] := 2 x/(1 + x^2 + y^2)^2 j2[x_, y_] := 2 y/(1 + x^2 + y^2)^2 j3[x_, y_] := (-1 + x^2 + y^2)/(1 + x^2 + y^2) toSphere[{x_, y_}] := {j1[x, y], j2[x, y], j3[x, y]} and Graphics3D[ g[[1]] /. GraphicsComplex[pnts_, more_, ___] :> GraphicsComplex[toSphere /@ pnts, more]] Regards Jens Cristina Ballantine wrote: > I would like to extract the points from the following ContourPlot > > g=ContourPlot[Arg[Gamma[x + I*y]] == 0, {x, -10, 10}, {y, -10, 10}, PlotPoints -> 100] > > I can do this with > > pts = First@Cases[g, x_GraphicsComplex :> First[x]] > > Then I would like to map this list of points onto the Riemann sphere. The projection is performed through > > j1[x_, y_] := 2 x/(1 + x^2 + y^2)^2 > j2[x_, y_] := 2 y/(1 + x^2 + y^2)^2 > j3[x_, y_] := (-1 + x^2 + y^2)/(1 + x^2 + y^2) > > I need to generate a list of three dimensional points (j1[x,y], j2[x,y], j2[x,y]) from pts and plot them. I am unable to generate the list of three dimensional points. Any help is very much appreciated. > > Cristina >