Re: Collecting Positive and Negative Terms

*To*: mathgroup at smc.vnet.net*Subject*: [mg112330] Re: Collecting Positive and Negative Terms*From*: "E. Martin-Serrano" <eMartinSerrano at telefonica.net>*Date*: Thu, 9 Sep 2010 04:24:46 -0400 (EDT)

This example illustrates the need of keeping constantly in mind that Mathematica actually works with expressions under FullForm. In[1]:== myExpression == a+b-c; In[2]:== FullForm[myExpression] Out[2]:== Plus[a,b,Times[-1,c]] In[3]:== DeleteCases[myExpression,Times[-1,___]] Out[3]:== a+b Of course, Times[-1,c] (in Out[2]) matches Times[-1,___] in (In[3]) Most times things get much more subtle and troublesome than this one if you try to understand an expression like this directly from its plain InputForm. So =BFwhat about a built-in button to pop-up a panel showing InputForm expressions converted to FullForm without the need of writing the 'In[2]' request explicitly as to see its inner structure? E. Martin-Serrano -----Original Message----- From: Michael Knudsen [mailto:micknudsen at gmail.com] Sent: Wednesday, September 08, 2010 7:00 AM To: mathgroup at smc.vnet.net Subject: [mg112330] [mg112301] Re: Collecting Positive and Negative Terms On Aug 14, 12:32 pm, Bob Hanlon <hanl... at cox.net> wrote: > myExpression == a + b - c; > > DeleteCases[myExpression, Times[-1, ___]] > > a+b Thanks! That was just what I needed! -- Michael Knudsen