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Re: Model the surface of an ellipsoid

  • To: mathgroup at smc.vnet.net
  • Subject: [mg93623] Re: Model the surface of an ellipsoid
  • From: Mayneord <xrayspectrum at googlemail.com>
  • Date: Tue, 18 Nov 2008 07:22:08 -0500 (EST)
  • References: <gfgqib$dm1$1@smc.vnet.net> <gfh3ca$g1d$1@smc.vnet.net>

On Nov 14, 12:36 pm, Jens-Peer Kuska <ku... at informatik.uni-leipzig.de>
wrote:
> Hi,
>
> after simple algebra you end up with
>
> R^2 == r^2 + R^2*d^2/D^2
>
> and since you have 4 variables, you
> can fix one of the variables
>
> With[{D = 1},
>   ContourPlot3D[
>    R^2 == r^2 + R^2*d^2/D^2, {r, -2, 2}, {R, -2, 2}, {d, -2, 2}]]
>
> or make an interactive version.
>
> Manipulate[
>   ContourPlot3D[
>    R^2 == r^2 + R^2*d^2/D^2, {r, -2, 2}, {R, -2, 2}, {d, -2,
>     2}], {D, -2, 2}]
>
> Regards
>    Jens
>
> Mayneord wrote:
> > On Nov 13, 12:34 pm, Jens-Peer Kuska <ku... at informatik.uni-leipzig.de>
> > wrote:
> >> Hi,
>
> >> and
>
> >>http://mathworld.wolfram.com/Ellipsoid.html
>
> >> has no parametric or implicit equation for you ?
> >> And you can't even download the notebookhttp://mathworld.wolfram.com/n=
ote=
> > books/Surfaces/Ellipsoid.nb
> >> ??
> >> Too bad
>
> >> Regards
> >>    Jens
>
> > Hi Jens,
>
> > Thank you so much for your reply.
> > when i wrote this post, I was sure that i will get a reply from you
> > first ;-)
>
> > I already download the notebook long ago.
> > I did not understand anything from that it seems to be too much of
> > mathematics to me.
> > In my case i have only 4 unknown parameters ( 1 = Sqrt[r^2/R^2 + d^2/
> > D^2] ). Typically, also shown in the websitehttp://mathworld.wolfram.co=
m/El=
> > lipsoid.html,
> > for a ellipsoidal there must at least three coordinates. But the
> > equation which is i have seems to be different. please tell me if am
> > wrong. Please understand i am using mathematica 5.2.
>
> > I used an ImplicitPlot like this i get only 2D plot.
> > ImplicitPlot[Sqrt[(x^2/9) + (y^2/4)] == 1, {x, -3, 3}]
>
> > My question is for 3D it is more complicated?  do i need to use much
> > of trigonometry for the angles?
>
> > thanks again
>
> > May

Hi Jens,

Thanks a lot for you help!
With ContourPlot3D it was very simple to model the whole volume of the
ellipse.

Thanks again !

With Regards,
Mayneord.


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