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MathGroup Archive 2000

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Re: global real variables

  • To: mathgroup at smc.vnet.net
  • Subject: [mg22039] Re: global real variables
  • From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
  • Date: Fri, 11 Feb 2000 02:38:20 -0500 (EST)
  • Organization: Universitaet Leipzig
  • References: <87trds$5o3@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Hi,

my Mathematica 4.0.1 reply for

FullSimplify[Conjugate[x + x*p^-1], Element[{x, p}, Reals]]

(1 + p^(-1))*x

But I agree that the Element relation should be an attribute to
a symbol. The best thing is to make a global variable
$mydomains={Element[{x,p},Reals] && Element[{i,j,k},Integers]}

and use

Simplify[expr,$mydomains]

during your calculation. Manly to avoid that you simplify with
the assumption x is real and two steps later you forgot this.

Hope that helps
  Jens

> 
>     Say I have tow var.s, x and p.  Both are real so I can do this.
> 
> Simplify[ Conjugate[ x ] , Element[ x , Reals ] ]  ----> x
> 
> amd I get the same thing for p, but it stops working if I have functions of
> x and p, for instance I get
> 
> Simplify[ Conjugate[ x + x * p^-1 ] , Element[ {x,p} , Reals ] ]  ---->
> 
>  Conjugate[ x + x * p^-1 ]
> 
> It works if I use FullSimplify   AND   put p^-1 into the list of variables
> that I want to have real.  How can I get around this without listing every
> negative power of every variable and wasting time with FullSimplify.  Thanks
> for any help.  Thanks.
> 
>                 -NAUM


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