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

*To*: mathgroup at smc.vnet.net*Subject*: [mg116353] 3D surface plots - non deletion of data inside undesirable Range*From*: Narasimham <mathma18 at hotmail.com>*Date*: Fri, 11 Feb 2011 04:19:20 -0500 (EST)

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

**Follow-Ups**:**Re: 3D surface plots - non deletion of data inside undesirable***From:*Daniel Lichtblau <danl@wolfram.com>

**Re: 3D surface plots - non deletion of data inside***From:*Heike Gramberg <heike.gramberg@gmail.com>