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Re: Simplify and Abs

• To: mathgroup at smc.vnet.net
• Subject: [mg54651] Re: Simplify and Abs
• From: "Jens-Peer Kuska" <kuska at informatik.uni-leipzig.de>
• Date: Fri, 25 Feb 2005 01:18:54 -0500 (EST)
• Organization: Uni Leipzig
• References: <cvk3fu$d6j$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

Hi,

PiecewiseExpand[Abs[p - 1], p < 1 && p > 1/2]

Regards

  Jens

"Simon Anders" <simon.anders at uibk.ac.at> schrieb im Newsbeitrag 
news:cvk3fu$d6j$1 at smc.vnet.net...
> Hi,
>
> can it really be that this is already beyond Mathematica?
>
>    In :=  FullSimplify[Abs[p - 1], p < 1 && p > 1/2]
>
>    Out := Abs[-1 + p]
>
> How do I make Matheamtica notice, that the assumptions constrain the
> argument of Abs[] to positive values?
>
> Any suggestions how to treat these kinds of problems? Specifically, I
> have a list of products of absolute values of simple polynomials in p
> and I know that p is in the interval [0,1].
>
> I would like to know whether the polynomials have constant sign over the
> interval so that the Abs[] can be removed. Can this be done automatically?
>
> TIA
>   Simon
>