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Re: how to identify plane and measuring planar area

  • To: mathgroup at smc.vnet.net
  • Subject: [mg69242] Re: how to identify plane and measuring planar area
  • From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
  • Date: Sun, 3 Sep 2006 23:46:26 -0400 (EDT)
  • Organization: The Open University, Milton Keynes, UK
  • References: <eddq5a$3t5$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

T Harris wrote:
> I am taking linear algebra and I have questions about the following code. 
> Can someone run it and help me here?  These are the two questions --> (1) 
> How do I measure the planar area of this flat thing?  (2)  What plane does 
> this ellipsoid plot out on?
> 
> What would I do in any case like this in the future to determine the plane? 
> Thanks for any help you can give.
> 
> In[566]:=
> {xstretch,ystretch,zstretch} = {1.5,0.8,0};
> ranger=1.5;
> {slow,shigh} = {0,Pi};
> {tlow,thigh} = {0,2 Pi};
> 
> hungellipsoidplot =
>   ParametricPlot3D[  xstretch   Sin[s]  Cos[t]  perpframe[1] +
>                      ystretch  Sin[s] Sin[t]  perpframe[2] +
>                      zstretch  Cos[s]perpframe[3], {s,slow,shigh},{t,tlow,
>       thigh},
> 
>     PlotRange->{{-ranger,ranger},{-ranger,ranger},{-ranger,ranger}},
>               Axes->True,AxesLabel->{"x","y","z"},
>               Boxed->False,ViewPoint->CMView,DisplayFunction->Identity];
> 
> setup =Show[hungellipsoidplot,frameplot,Axes3D[ranger],
>       DisplayFunction->$DisplayFunction];
> 
> 
> 
> Show[setup, ViewPoint -> 12 perpframe[1]]; 
> 

Could you, please, post something that works -- your code does not work 
at all -- or at least post all the required definitions -- definitions 
of perpframe and CMView are missing -- and possibly something that is 
syntacticly correct -- say a list of three functions when a list of 
three functions is expected rather than the sum of three functions -- 
and also meaningful -- the Show of the Show command, even in disguised 
of a setup expression, is quite meaningless -- ?

Here is the last of my attempts -- at least you get a plot -- before I 
gave up:

Evaluate[Array[perpframe, 3]] = {1, 2, 3}
CMView = {1.3, -2.4, 2};
  { xstretch,ystretch,zstretch}= { 1.5,0.8,0};
  ranger=1.5;
  { slow,shigh}= { 0,Pi};
  { tlow,thigh}= { 0, 2 Pi};\[IndentingNewLine]
  hungellipsoidplot= ParametricPlot3D[ { xstretch Sin[s] Cos[t] 
perpframe[1], ystretch Sin[s] Sin[t] perpframe[2], zstretch Cos[s] 
perpframe[3]}, { s,slow,shigh}, { t,tlow,thigh}, PlotRange-> { { 
-ranger,ranger}, { -ranger,ranger}, { -ranger,ranger}}, Axes->True, 
AxesLabel-> { "x","y","z"}, Boxed->False, ViewPoint->CMView];

HTH,
Jean-Marc


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