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Re: Simplify[Abs[x],x<0]]

• To: mathgroup at smc.vnet.net
• Subject: [mg39315] Re: [mg39303] Simplify[Abs[x],x<0]]
• From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
• Date: Tue, 11 Feb 2003 04:41:20 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

Almost certainly an oversight. However, if you replace Abs by something 
equivalent, things work as they should, e.g:


Simplify[Sqrt[x*Conjugate[x]], x < 0]

-x

or


Simplify[Sqrt[Im[x]^2 + Re[x]^2], x < 0]

-x

etc.




On Monday, February 10, 2003, at 03:07 PM, Uri Zwick wrote:

> Hi,
>
> Simplify[ Abs[x] , x>0 ] returns x.
> But, Simplify[ Abs[x] , x<0] returns Abs[x], and not -x.
>
> Why is that?
>
> Uri
>
>
>
>
Andrzej Kozlowski
Yokohama, Japan
http://www.mimuw.edu.pl/~akoz/
http://platon.c.u-tokyo.ac.jp/andrzej/