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Re: checking the sign of all terms in a long expression
*To*: mathgroup at smc.vnet.net
*Subject*: [mg132566] Re: checking the sign of all terms in a long expression
*From*: Bob Hanlon <hanlonr357 at gmail.com>
*Date*: Sat, 12 Apr 2014 05:15:59 -0400 (EDT)
*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com
*Delivered-to*: l-mathgroup@wolfram.com
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*References*: <20140411061009.8DE2B6A30@smc.vnet.net>
Depnding on your intent:
toCheck = a + a b + a b c + a c - b + b c + d - e (f + g);
Cases[toCheck, Times[-1, __]]
{-b, -e (f + g)}
Cases[toCheck // ExpandAll, Times[-1, __]]
{-b, -e f, -e g}
Bob Hanlon
On Fri, Apr 11, 2014 at 2:10 AM, dantimatter <google at dantimatter.com> wrote:
>
> hello all
> is there to check the signs of all terms in a symbolic expression, like
>
> toCheck = a + a b + a b c + a c - b + bc + d ....
>
> in this case, with the assumption that the a, b, c etc are all positive,
> only one term is negative (b by itself) and the rest are positive. I have
> expressions like this that have a hundred or more terms and i'm worried i
> might not be catching all those that are of a different sign.
>
> thanks
>
>
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