RE: ParametricPlot3D is buggy

*To*: mathgroup at smc.vnet.net*Subject*: [mg25245] RE: [mg25223] ParametricPlot3D is buggy*From*: "David Park" <djmp at earthlink.net>*Date*: Sun, 17 Sep 2000 04:47:23 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

Will, This does look like a bug in the Mathematica graphics. For some reason Mathematica's algorithim for automatically picking the PlotRange has misfired. plot2 = ParametricPlot3D[{Cos[t]Cos[u], Sin[t]Cos[u], Sin[u]}, {t, 0, 2Pi}, {u, -Pi/2, Pi/2}, PlotPoints -> {7, 3}, PlotRange -> Automatic]; (a plot but no polyhedron) FullOptions[plot2, PlotRange] {{-1.05, 1.05}, {-3.141996211819542*^-15, 2.131357156737179*^-15}, {-1.05, 1.05}} You will get a proper plot if your choose PlotRange -> All. Of course, you are using ParametricPlot3D to render polyhedrons by using a low number of plot points. ParametricPlot3D probably wasn't designed with that in mind. But PlotRange -> All or a specific PlotRange should solve the problem. David Park djmp at earthlink.net http://home.earthlink.net/~djmp/ > -----Original Message----- > From: Will Self [mailto:wself at msubillings.edu] To: mathgroup at smc.vnet.net > Can anyone explain this bug that appears in ParametricPlot3D > in my version of Mathematica 4.0.2 on Windows 2000? > > ----------------------------------------------------------- > > This works fine: > > ParametricPlot3D[{Cos[t]Cos[u], Sin[t]Cos[u], Sin[u]}, > {t, 0, 2Pi}, {u, -Pi/2, Pi/2}, PlotPoints -> {8, 3}] > > But this doesn't give a picture: > > ParametricPlot3D[{Cos[t]Cos[u], Sin[t]Cos[u], Sin[u]}, > {t, 0, 2Pi}, {u, -Pi/2, Pi/2}, PlotPoints -> {7, 3}] > >