Re: Incomplete simplification

*To*: mathgroup at smc.vnet.net*Subject*: [mg49287] Re: [mg49285] Incomplete simplification*From*: Andrzej Kozlowski <akoz at mimuw.edu.pl>*Date*: Mon, 12 Jul 2004 02:11:28 -0400 (EDT)*References*: <200407110616.CAA16721@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

On 11 Jul 2004, at 15:16, Carlos Felippa wrote: > *This message was transferred with a trial version of CommuniGate(tm) > Pro* > Using Mathematica 4.2 on a mac I defined a 6 x 3 symbolic > matrix and take its Moore-Penrose inverse: > > S={{0,-x31,x21},{x31,0,-x11},{-x21,x11,0},{0,-x32,x22}, > {x32,0,-x12},{-x22,x12,0}}; > G=PseudoInverse[S]; > > Mathematica thinks the entries are complex, so it returns a > result with Conjugate[x11], etc. To get rid of them I tried > > G=Simplify[G,x11\[Element]Reals&&x21\[Element]Reals <...> ]; > > But the Conjugate[...] are still there. Fortunately G=ComplexExpand[G] > works. But why is Simplify unable to use the reality assumptions? In my case (both in Mathematica 5.0 and 4.2) S = {{0, -x31, x21}, {x31, 0, -x11}, {-x21, x11, 0}, {0, -x32, x22}, {x32, 0, -x12}, {-x22, x12, 0}}; G = PseudoInverse[S]; Simplify[G, Element[_, Reals]] produces an answer without any Conjugates. Sounds like there was something wrong with your input. Andrzej Kozlowski Chiba, Japan http://www.mimuw.edu.pl/~akoz/

**References**:**Incomplete simplification***From:*carlos@colorado.edu (Carlos Felippa)