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MathGroup Archive 1997

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Re: Help: Implicit 3D function

  • To: mathgroup at smc.vnet.net
  • Subject: [mg8012] Re: [mg7950] Help: Implicit 3D function
  • From: "Keith S. Mersman" <c621746 at everest.cclabs.missouri.edu>
  • Date: Wed, 30 Jul 1997 23:58:09 -0400
  • Sender: owner-wri-mathgroup at wolfram.com

Claus,

One way I can think of doing this is to solve for z = + or -
Sqrt[30(1-x^2/10-y^2/20)] and then use Plot3D or ParametricPlot3D with
these two functions of x and y.

However, there is an easier way.  Using modified spheical coordinates we
see that if 

x= Sqrt[10] Sin[s] Cos[t]
y= Sqrt[20] Sin[s] Sin[t]
z= Sqrt[30] Cos[s]

where s varies from 0 to Pi and t varies from 0 to 2 Pi, 

then this is a parametrization of the ellipsoid x^2/10+y^2/20+z^2/30=1
Then you can use ParametricPlot3D for this parametrization.



On Fri, 25 Jul 1997, Claus Wisser wrote:

> Hello,
> 
> I'm new to Mathematica and hopefully there is someone out there who can
> help me.
> I would like to plot a a implict 3D-function, e.g. x^2/10+y^2/20+z^2/30=1.
> Please, can someone help me and tell me how to do it.
> 
> Thank you,
> Claus
> 
> Claus.Wisser at studbox.uni-stuttgart.de
> 
> 



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