Re: Are some equations unsolvable?

*To*: mathgroup at smc.vnet.net*Subject*: [mg128068] Re: Are some equations unsolvable?*From*: "Kevin J. McCann" <kjm at KevinMcCann.com>*Date*: Thu, 13 Sep 2012 03:38:44 -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*References*: <k2pc54$99t$1@smc.vnet.net>

A quick look at your function indicates that you have Sqrt[Pi/(-1/(2 sigma^2)))], which will give you an complex number for real sigma. Kevin On 9/12/2012 3:04 AM, Sergio Sergio wrote: > Hi, > This is what I have: > > f = (1/(sigma*Sqrt[2 Pi]))*Sqrt[(Pi/(-1/(2*sigma^2)))]* > Exp[((m/sigma^2)^2)/4*(-1/2*sigma^2) + (m^2/(2*sigma^2))] > > Solve[f == 216, sigma] > > And I get this message: "This system cannot be solved with the methods available to Solve" > > Is it because there is no way to isolate sigma? Or am I doing something wrong? > > Thanks >