Re: 3D surface plots - non deletion of data inside undesirable Range

*To*: mathgroup at smc.vnet.net*Subject*: [mg116373] Re: 3D surface plots - non deletion of data inside undesirable Range*From*: "Sjoerd C. de Vries" <sjoerd.c.devries at gmail.com>*Date*: Sat, 12 Feb 2011 05:19:28 -0500 (EST)*References*: <ij2uvf$7u3$1@smc.vnet.net>

Just add an exclusion to the second graph and you're set: GL2 = ParametricPlot3D[gl, {th, -Pi/3, Pi/3}, {ph, -Pi/3, Pi/3}, PlotRange -> {{-3, 3}, {-3, 3}, {-3, 3}}, Exclusions -> Cos[ph + th] == 0] The problem here is the division by zero in places where Cos[ph + th] == 0. Cheers -- Sjoerd On Feb 11, 10:19 am, Narasimham <mathm... at hotmail.com> wrote: > a=2;b=1;c=3;gl={a Cos[ph-th],b Sin[ph-th],c Sin[ph+th]}/Cos[ph+th= ]; > GL1=ParametricPlot3D[gl,{th,-Pi/4,Pi/4},{ph,-Pi/4,Pi/4},PlotRange->{{-3,3},{-3,3},{-3,3}}] > > GL2=ParametricPlot3D[gl,{th,-Pi/3,Pi/3},{ph,-Pi/3,Pi/3},PlotRange->{{-3,3},{-3,3},{-3,3}}] > > Show[GL1,GL2] > > Extended plot limits in GL2 beyond those of GL1 result in 3D plot that > fail to delete undesired spurious tracing/tracking data between points > not lying on the required surface.Like 'pen up' data in earlier > graphing s/w. It is OK may be to plot an enclosed solid, but not for a > surface. The difficulty also appeared in earlier Mathematica versions. > Is there then, no work around possible? > > Best Regards > Narasimham