Date: Nov 24, 2012 2:30 AM
Author: Eduardo Mendes
Subject: Re: Is there way to use something like Assuming with the function SIgn?
Hello

Many thanks.

Ed

On Nov 23, 2012, at 12:01 PM, Bob Hanlon <hanlonr357@gmail.com> wrote:

> "Assuming[assum, expr] evaluates expr with assum appended to

> $Assumptions, so that assum is included in the default assumptions

> used by functions such as Refine, Simplify, and Integrate."

>

> list = {1, -2, a, 3};

>

> Assuming[a < 0, Simplify[Sign[list]]]

>

> {1, -1, -1, 1}

>

> However, more compactly

>

> Simplify[Sign[list], a < 0]

>

> {1, -1, -1, 1}

>

>

> Bob Hanlon

>

>

> On Fri, Nov 23, 2012 at 3:25 AM, Eduardo Mendes <emammendes@hotmail.com> wrote:

>> Hello

>>

>> I was wondering there is something similar to what can be done with Integrate, Reduce and Limit. Something like

>>

>> list={1,-2,a,3}

>>

>> Assuming[a<0,Sign[list]]

>>

>> Mathematica returns {1,-1,Sign[a],1} and I would like to see something like {1,-1,-1,1}. Can that be done?

>>

>> Many thanks

>>

>> Ed

>>

>>

>