Infrequent Mathematica User

• To: mathgroup at smc.vnet.net
• Subject: [mg47037] Infrequent Mathematica User
• From: "Jim Dars" <jim-dars at comcast.net>
• Date: Mon, 22 Mar 2004 05:18:48 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

```Hi All,

f is a defined below as a function of x, y, and z.
I wish to take the partials set to zero and solve the 3 equations for x, y,
and z.
I've copied from Mathematica and had to clean up the paste, a bit.  I used
the partial symbol from the palette to define my partial derivatives.  The 3
I've tried the "Solve equation" with just "a" and a[x_,y_,z_] etc.
Mathematica replies {{}}.
I sure would appreciate some advice.

Thanks, Best wishes, Jim
Jim-Dars at comcast.net

f[x_, y_, z_] =
x/(1 + x^2) + y/(1 + x^2 + y^2) +
z/(1 + x^2 + y^2 + z^2);
a[x_, y_, z_] = \[PartialD]\_x f;\)\[IndentingNewLine]
b[x_, y_, z_] = \[PartialD]\_y f;\)\[IndentingNewLine]
c[x_, y_, z_] = \[PartialD]\_z\ f;\)\[IndentingNewLine]
Solve[{a[x_, y_, z_] == 0, b[x_, y_, z_] == 0, c[x_, y_, z_] == 0}, {x, y,
z}]

```

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