Re: Re: Weird result in Mathematica 6

*To*: mathgroup at smc.vnet.net*Subject*: [mg76477] Re: [mg76431] Re: [mg76393] Weird result in Mathematica 6*From*: Andrzej Kozlowski <akoz at mimuw.edu.pl>*Date*: Wed, 23 May 2007 05:09:39 -0400 (EDT)*References*: <26727995.1179743868970.JavaMail.root@m35> <200705220647.CAA19795@smc.vnet.net>

I don't see any connection between these two issues. Moreover, I get: FindRoot[h == g, {x, 0}] FindRoot::njnum:The Jacobian is not a matrix of numbers at {x} = {0.}. >> {x -> 0.} which explains what is wrong (error messages can tell you a lot, sometimes). Trying a slightly different starting search point: FindRoot[h == g, {x, 0.1}] {x->2.} {g, h} /. % {0., 0.} Andrzej Kozlowski On 22 May 2007, at 15:47, DrMajorBob wrote: > Even worse, FindRoot returns a wrong answer: > > g = Piecewise[{{0, x < 0}, {2 x - x^2, 0 <= x < 4}, {16 x - x^2, > x=B34}}]; > h = x - 2; > FindRoot[h == g, {x, 0}] > {g, h} /. % > > {x->-2.84217*10^-15} > {0, -2.} > > Bobby > > On Mon, 21 May 2007 05:01:21 -0500, Sebastian Meznaric > <meznaric at gmail.com> 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? >> >> >> > > > > -- > DrMajorBob at bigfoot.com >

**References**:**Re: Weird result in Mathematica 6***From:*DrMajorBob <drmajorbob@bigfoot.com>