Re: imposing parameter assumptions
- To: mathgroup at smc.vnet.net
- Subject: [mg44198] Re: imposing parameter assumptions
- From: bobhanlon at aol.com (Bob Hanlon)
- Date: Sun, 26 Oct 2003 00:41:52 -0400 (EDT)
- References: <bndkco$g6f$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Use Simplify
f[a]=a^-3;
Simplify[#[f[a]], a<0]& /@
{Sign, Positive, Negative, NonNegative}
{-1,False,True,False}
Bob Hanlon
In article <bndkco$g6f$1 at smc.vnet.net>, "drr7" <rondeau at uvic.ca> wrote:
<< 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.
>><BR><BR>