Re: Plotting a x,y,z function

*To*: mathgroup at smc.vnet.net*Subject*: [mg98702] Re: Plotting a x,y,z function*From*: "Sjoerd C. de Vries" <sjoerd.c.devries at gmail.com>*Date*: Thu, 16 Apr 2009 04:17:58 -0400 (EDT)*References*: <gs47lm$7p3$1@smc.vnet.net>

Of course you have to specify that r = Sqrt[x^2+y^2+z^2]. r is just a letter that sometimes is used to denote radius but it may serve millions of other purposes. How do you think Mathematica could guess what you're using it for? r[x_, y_, z_] = Sqrt[x^2 + y^2 + z^2]; f[x_, y_, z_] = (x^2 + y^2 + z^2) E^-(r[x, y, z]^2/2); ContourPlot3D[f[x, y, z], {x, -10, 10}, {y, -10, 10}, {z, -10, 10}] In your definition of f you used the lowercase e which hasn't a special meaning, use esc-ee-esc or E instead. Cheers -- Sjoerd On Apr 15, 10:59 am, chem_chick <raeanne.napol... at gmail.com> 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? Or do I have to define r in terms > of x,y,z somehow?! Help with syntax will be great! > > Thanks!