AW: Infrequent Mathematica User

*To*: mathgroup at smc.vnet.net*Subject*: [mg47059] AW: [mg47048] Infrequent Mathematica User*From*: Matthias.Bode at oppenheim.de*Date*: Mon, 22 Mar 2004 22:39:16 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

Hello Jim, applying the KIS principle, try: Clear[x, y, z] func = x/(1 + x^2) + y/(1 + x^2 + y^2) + z/(1 + x^2 + y^2 + z^2); dfx = D[func, x]; dfy = D[func, y]; dfz = D[func, z]; Reduce[dfx == 0 && dfy == 0 && dfz == 0, x] N[%] Best regards, Matthias Bode Sal. Oppenheim jr. & Cie. KGaA Koenigsberger Strasse 29 D-60487 Frankfurt am Main GERMANY Tel.: +49(0)69 71 34 53 80 Mobile: +49(0)172 6 74 95 77 Fax: +49(0)69 71 34 95 380 E-mail: matthias.bode at oppenheim.de Internet: http://www.oppenheim.de -----UrsprÃ¼ngliche Nachricht----- Von: Jim Dars [mailto:jim-dars at comcast.net] Gesendet: Montag, 22. MÃ¤rz 2004 11:19 An: mathgroup at smc.vnet.net Betreff: [mg47048] Infrequent Mathematica User Hi All, (second post, first didn't display) f is 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 lines on this page look nothing like what appeared when using Mathematica to obtain the partials. 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}]