Re: Re: Weird result in Mathematica 6

*To*: mathgroup at smc.vnet.net*Subject*: [mg76631] Re: [mg76603] Re: Weird result in Mathematica 6*From*: Andrzej Kozlowski <akoz at mimuw.edu.pl>*Date*: Fri, 25 May 2007 06:24:12 -0400 (EDT)*References*: <200705211001.GAA10071@smc.vnet.net> <200705241018.GAA21697@smc.vnet.net>

Applying ComplexExpand[] to real assumptions and ComplexExpand[ , {x}] to complex ones will normally avoid such problems: Simplify[Im[x], Assumptions -> {ComplexExpand[x - Conjugate[x] > 0, {x}]}] Im(x) Andrzej Kozlowski On 24 May 2007, at 19:18, Sebastian Meznaric wrote: > Another related effect can be used to actually derive contradictions > in Mathematica. Try this > Simplify[Im[x],Assumptions->{x-Conjugate[x]>0}] > > It returns 0. The assumption was that Im[x]>0 so here Mathematica > clearly contradicts the assumption. > > Obviously this suggests one should be very careful when using > inequalities with complex quantities. I think this sort of bugs should > really be fixed considering how much trouble Mathematica usually goes > into to ensure that real quantities are not assumed in expressions. > >

**References**:**Weird result in Mathematica 6***From:*Sebastian Meznaric <meznaric@gmail.com>

**Re: Weird result in Mathematica 6***From:*Sebastian Meznaric <meznaric@gmail.com>