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Re: Is there way to use something like Assuming with the function SIgn?

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  • Subject: [mg128764] Re: Is there way to use something like Assuming with the function SIgn?
  • From: Bill Rowe <readnews at sbcglobal.net>
  • Date: Sat, 24 Nov 2012 02:26:46 -0500 (EST)
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On 11/23/12 at 3:25 AM, emammendes at hotmail.com (Eduardo Mendes)
wrote:

>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?


Assuming only affects the operation of a few functions in
Mathematica such as Simplify. So,

In[19]:= Clear[a];
list = {1, -2, a, 3};
Assuming[a < 0, Simplify[Sign[list]]]

Out[21]= {1,-1,-1,1}




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