Re: Weird result in Mathematica 6

*To*: mathgroup at smc.vnet.net*Subject*: [mg76415] Re: Weird result in Mathematica 6*From*: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>*Date*: Tue, 22 May 2007 02:39:14 -0400 (EDT)*Organization*: Uni Leipzig*References*: <f2rqvi$9uo$1@smc.vnet.net>*Reply-to*: kuska at informatik.uni-leipzig.de

Hi, because you have not given an domain. But Reduce[(z - a)/(1 - a\[Conjugate] z) == w && a a\[Conjugate] < 1 && w w\[Conjugate] < 1, z, Complexes] does this. Regards Jens Sebastian Meznaric wrote: > I was playing around with Mathematica 6 a bit and ran this command to > solve for the inverse of the Moebius transformation > > FullSimplify[ > Reduce[(z - a)/(1 - a\[Conjugate] z) == w && a a\[Conjugate] < 1 && > w w\[Conjugate] < 1, z]] > > This is what I got as a result: > -1 < w < 1 && -1 < a < 1 && z == (a + w)/(1 + w Conjugate[a]) > > Why is Mathematica assuming a and w are real? The Moebius > transformation is invertible in the unit disc regardless of whether a > and w are real or not. Any thoughts? > >