Re: Infrequent Mathematica User
- To: mathgroup at smc.vnet.net
- Subject: [mg47055] Re: Infrequent Mathematica User
- From: bobhanlon at aol.com (Bob Hanlon)
- Date: Mon, 22 Mar 2004 22:39:10 -0500 (EST)
- References: <c3mfek$r7l$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
f[x_,y_,z_]:=x/(1+x^2)+y/(1+x^2+y^2)+z/(1+x^2+y^2+z^2); eqns = Thread[Simplify[ D[f[x,y,z],#]& /@ {x,y,z}]==0]; FindRoot[eqns,{{x,1},{y,1},{z,1}}] {x -> 0.6096239644159589, y -> 0.8626792159182006, z -> 1.4545985039066525} NSolve[eqns, {x,y,z}] {{x -> -1.1504610099495616, y -> 2.389556579417945, z -> -2.8343502221238883}, {x -> 1.1504610099495591, y -> -2.3895565794179503, z -> 2.8343502221238954}, {x -> -0.8844004241635046, y -> -2.0927346690454693, z -> 2.4822776849670647}, {x -> 0.8844004241635126, y -> 2.0927346690454627, z -> -2.482277684967057}, {x -> 3.4547344369933075, y -> -2.649204308160977, z -> -4.4669311049675535}, {x -> -3.454734436993219, y -> 2.6492043081608667, z -> 4.466931104967412}, {x -> -0.6096239644159579, y -> -0.8626792159182, z -> -1.4545985039066518}, {x -> 0.6096239644159587, y -> 0.8626792159181986, z -> 1.4545985039066525}} Bob Hanlon In article <c3mfek$r7l$1 at smc.vnet.net>, "Jim Dars" <jim-dars at comcast.net> wrote: << 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 lines on this page look nothing like what I feed Mathematica. 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}] >><BR><BR>