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Re: imposing parameter assumptions

  • To: mathgroup at
  • Subject: [mg44196] Re: [mg44184] imposing parameter assumptions
  • From: "Peter Pein" <nospam at>
  • Date: Sun, 26 Oct 2003 00:41:50 -0400 (EDT)
  • References: <>
  • Sender: owner-wri-mathgroup at

Simplify[Sign[a^-3], a < 0]

use FullSimplify for harder problems.

Peter Pein, Berlin
petsie at
replace && by || to write to me

----- Original Message -----
From: "drr7" <rondeau at>
To: mathgroup at
Subject: [mg44196] [mg44184] imposing parameter assumptions

> Simple question:  How do I impose assumptions on the sign of parameters in
> symbolic equations and then test for the sign of an expression. Example:
> suppose I want to test the sign of f[a]=a^-3 if a<0.  I tried combinations
> of Refine and Positive, but that does not seem to work for me.  What I am
> really trying to do is sign a long expression for a derivative.
> Thanks.

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