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Re: how to visualize 3+D normal density contour?


Here are 3 examples of what you want:

<<Graphics`ContourPlot3D`

Spherical case:

ContourPlot3D[Exp[-{x, y, z} . {{1, 0, 0}, {0, 1, 0}, {0, 0, 1}} .
       {x, y, z}] - 0.5, {x, -1, 1}, {y, -1, 1}, {z, -1, 1}];

Axis-aligned ellipsoidal case:

ContourPlot3D[Exp[-{x, y, z} . {{1, 0, 0}, {0, 2, 0}, {0, 0, 4}} .
       {x, y, z}] - 0.5, {x, -1, 1}, {y, -1, 1}, {z, -1, 1}];

More general ellipsoidal case:

ContourPlot3D[Exp[-{x, y, z} . {{2, 2, 1}, {0.5, 2, 1}, {1, 2, 4}} .
       {x, y, z}] - 0.5, {x, -1, 1}, {y, -1, 1}, {z, -1, 1}, PlotPoints -> 
5];

Steve Luttrell

"gino" <loseminds at hotmail.com> wrote in message 
news:dru754$a18$1 at smc.vnet.net...
> Hi all,
>
> How do I visualize a contour of a tri-variate normal distribution?
>
> I just like to see the ellipsoid very much. I hope there is a easy way or
> existing method.
>
> Thank you a lot!
>
>
> 



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