Re: Reduce command Mathematica

*To*: mathgroup at smc.vnet.net*Subject*: [mg128264] Re: Reduce command Mathematica*From*: Dana DeLouis <dana01 at me.com>*Date*: Mon, 1 Oct 2012 02:23:06 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-newout@smc.vnet.net*Delivered-to*: mathgroup-newsend@smc.vnet.net

> Reduce[2 n - Tanh[z] Tanh[2 n z] == 0, z] Hi. I can't get this to work either. Here's a technique when working with 1 equation, and 2 variables. You are looking for the contour of 0. (Mouse over the 0 line in the chart for confirmation) equ=2 n-Tanh[z] Tanh[2 n z]; ContourPlot[ equ,{n,-2,2},{z,-3,3}, Contours->Range[-4,4], CoordinatesToolOptions->Automatic, FrameLabel->{"n","z"} ] As you can see, the obvious solution is n=0. But, there is also a solution near the top and bottom with -.5 < n <+.5 Sometimes, putting further constraints works, but it doesn't work here: Reduce[{equ == 0 , -1/2 < n < 1/2}, z, Reals] << No Luck >> For example, if n = 1 / 4, then it won't catch the solution for z of Log[2+Sqrt[3]] : equ /. {n -> 1 / 4, z-> Log[2+Sqrt[3]]} //FullSimplify 0 Hopefully, someone can jump in with a better idea: = = = = = = = = = = HTH :>) Dana DeLouis Mac & Mathematica 8 = = = = = = = = = = On Thursday, September 27, 2012 11:06:13 PM UTC-4, Oznur Oztunc wrote: > Hi, > > I have the following system.Why isn't Reduce able to find the solution? I have tried some command (Solve). But I can't be solve this equation. > > Reduce[2 n - Tanh[z] Tanh[2 n z] == 0, z] > > > > Regards, and thanks to all who will answer! > > =D6snur =D6stun=E7