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Re: Is there way to use something like Assuming with the function SIgn?
*To*: mathgroup at smc.vnet.net
*Subject*: [mg128776] Re: Is there way to use something like Assuming with the function SIgn?
*From*: "Eduardo M. A. M. Mendes" <emammendes at hotmail.com>
*Date*: Sat, 24 Nov 2012 02:30:47 -0500 (EST)
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*References*: <20121123082533.A76536891@smc.vnet.net> <CAEtRDScjm0mpXcwfkuKfASSTUQUuN3DKeXCYJuOZNCehFKRw7A@mail.gmail.com>
Hello
Many thanks.
Ed
On Nov 23, 2012, at 12:01 PM, Bob Hanlon <hanlonr357 at 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 at 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
>>
>>
>
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