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Re: Display selected region of a table of polygons

  • To: mathgroup at smc.vnet.net
  • Subject: [mg107924] Re: Display selected region of a table of polygons
  • From: dh <dh at metrohm.com>
  • Date: Wed, 3 Mar 2010 05:49:38 -0500 (EST)
  • References: <hmiipe$3vu$1@smc.vnet.net>

Hi Dominic,
you can do much better than polygons with less effort using 
Parametricplot3D:
ParametricPlot3D[{r Sin[phi], r Cos[phi], Im[Sin[r Exp[I phi]]]}, {r,
   1.2, 2}, {phi, 0, 2Pi}]
and for part of the circle:
ParametricPlot3D[{r Sin[phi], r Cos[phi], Im[Sin[r Exp[I phi]]]}, {r,
   1.2, 2}, {phi, 1.2, 2.5}]

Daniel


On 02.03.2010 09:38, Dominic wrote:
> Hello,
>
> Can someone tell me if there is a way to display a selected angular
> region of a table of polygons representing a surface?  I don't think
> RegionFunction, Exclusion, or RegionPlot can do this.  Not sure though.
> For example, the code below creates a table of polygons representing
> Im[Sin[z]] in a circle of radius two.  Suppose now I only want to
> display the surface between angles startT=1.2 and endT=2.5
> (radians).  I don't know how to do this other than re-acquire the data
> between those two angles but the actual application I'm writing already
> has the data conveniently acquired in the 2pi region.
>
> Thanks guys,
>
> Dominic
>
> f[z_] := Sin[z];
> mypTable = Table[{r*Cos[t], r*Sin[t], Im[f[r*Exp[I*t]]]},
> {r, 0.001, 2, 0.1}, {t, 0, 2*Pi, Pi/10}];
> tval = Length[mypTable]
> rval = Length[mypTable[[1]]]
> myPolygons = Table[Polygon[{mypTable[[i, j]], mypTable[[i + 1, j]],
> mypTable[[i + 1, j + 1]], mypTable[[i, j + 1]]}],
> {j, 1, rval - 1}, {i, 1, tval - 1}];
> pic1 = Show[Graphics3D[myPolygons]]
>
>
>


-- 

Daniel Huber
Metrohm Ltd.
Oberdorfstr. 68
CH-9100 Herisau
Tel. +41 71 353 8585, Fax +41 71 353 8907
E-Mail:<mailto:dh at metrohm.com>
Internet:<http://www.metrohm.com>



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