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Re: Plot3D Problem with Nonreal Numbers

  • To: mathgroup at
  • Subject: [mg20079] Re: Plot3D Problem with Nonreal Numbers
  • From: "Stephen P Luttrell" <luttrell at>
  • Date: Wed, 29 Sep 1999 03:33:32 -0400
  • Organization: Defence Evaluation and Research Agency
  • References: <7shqcb$>
  • Sender: owner-wri-mathgroup at

> All I
> have is a sketch of something that resembles two funnels joined at the
> narrow end and this equation:
> x^2 - y^2 + z^2 = 4
> I have solved for z and used the results in Plot3D but this generates an
> error for the points that are not real numbers and only a portion of the
> plot is drawn.
> The question is, is there a way to make Mathematica ignore the solutions
> that are not real?

Preamble: I have $Version = "4.0 for Microsoft Windows (April 21, 1999)"

You need to use ContourPlot3D.

First read in the Graphics`ContourPlot3D` package thus:

<< Graphics`ContourPlot3D`

Then execute the following:

ContourPlot3D[x^2 - y^2 + z^2 - 4, {x, -6, 6}, {y, -6, 6}, {z, -6, 6}];

which gives you something like what you want.

Check out the information on ContourPlot3D in the Help browser for various
options that you can use to change the way things are plotted.

Dr Stephen P Luttrell
Room EX21, Defence Evaluation and Research Agency
Malvern, Worcs, WR14 3PS, U.K.
luttrell at
01684-894046 (phone), 01684-894384 (fax)

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