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Re: Strain Ellipsoids

  • To: mathgroup at smc.vnet.net
  • Subject: [mg17928] Re: Strain Ellipsoids
  • From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
  • Date: Sat, 5 Jun 1999 02:56:01 -0400
  • Organization: Universitaet Leipzig
  • References: <7j5alm$g48@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Hi,

You havt to transform the *points* not the polygons
The following works:

strain=DiagonalMatrix[{2,3,4}];
Show[
  Graphics3D[
    Sphere[]/. Polygon[p_]:> Polygon[Dot[strain,#] & /@ p]
   ]
 ];

Hope that helps
  Jens


Mark Lawrence Storch wrote:
> 
> Hi,
>     I am trying to write a code that will draw the strain ellipsoid for
> a given strain tensor.  I was starting with the `Graphics`Shapes package
> to get the Sphere[] function.  I want a function that will return a list
> that I can use with Show[].  Sphere gives me polygons and I have tried
> the following:
> 
> StrainEllipsoid[m_?MatrixQ]:=(m.#)&/@Sphere[]
> 
> but I keep getting an error that reads
> 
> Show::gcomb : An error was encountered in combining the graphics objects
> in Show[{<<1>>}]
> 
> I am new to using # and /@ so any help here would be appreciated.
> 
> Thank you,
> Mark Storch
> Carnegie Mellon University


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