       Re: Plotting a x,y,z function

• To: mathgroup at smc.vnet.net
• Subject: [mg98706] Re: Plotting a x,y,z function
• From: Bill Rowe <readnews at sbcglobal.net>
• Date: Thu, 16 Apr 2009 04:18:41 -0400 (EDT)

```On 4/15/09 at 4:59 AM, raeanne.napoleon at gmail.com (chem_chick) wrote:

>I needed help plotting the following function:

>f[x_,y_,z_] = (x^2+y^2+z^2) e^-(r^2/2)

>ContourPlot3D[(x^2 + y^2 - z^2) Exp[-r^2/2], {x, -10, 10}, {y, -10,
>10}, {z, -10, 10}]

>does not work because it doesn't understand what r (radius)
>is....what is the keyword/whatever for radius?

There is none.

>Or do I have to define r in terms of x,y,z somehow?!

Yes.

>Help with syntax will be great!

Assuming standard cartesian coordinates, then r^2 should be
x^2+y^2+z^2 and the following code will give you the desired graphic

ContourPlot3D[(x^2 + y^2 - z^2) Exp[-(x^2 + y^2 - z^2)/2], {x, -10,
10}, {y, -10, 10}, {z, -10, 10}]

Or, the function you wrote when corrected as folllows:

f[x_,y_,z_] = (x^2+y^2+z^2) E^-((x^2 + y^2 - z^2)/2)

can be used to create the graphic using

ContourPlot3D[f[x,y,z], {x, -10,
10}, {y, -10, 10}, {z, -10, 10}]

```

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