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checking the sign of all terms in a long expression

  • To: mathgroup at smc.vnet.net
  • Subject: [mg132555] checking the sign of all terms in a long expression
  • From: dantimatter <google at dantimatter.com>
  • Date: Fri, 11 Apr 2014 02:10:09 -0400 (EDT)
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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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