Re: How to select terms wanted in a series

*To*: mathgroup at smc.vnet.net*Subject*: [mg85951] Re: How to select terms wanted in a series*From*: Bhuvanesh <BhuvaneshBhatt at gmail.com>*Date*: Thu, 28 Feb 2008 02:56:18 -0500 (EST)*References*: <fq3bhj$gas$1@smc.vnet.net>

On Feb 27, 3:46 am, Barrow <GRsemi... at gmail.com> wrote: > Dear all, > > I have an expression, which is a sum of large number of terms, e.g. > > expression = x + 2x*y - x*y*z + u*x*y + 3u^2 > > And I want to select out terms with the factor (x*y). e.g. > > The terms in "expression" that I want are 2x*y, -x*y*z, u*x*y > > My first step is, > > allterms = Apply[List, expression] > > Then, I don't know how to extract the terms I want, I use > > Select[allterms, (# == x*y*_)&] > > But It doesn't work. > > Anyone has some good ideas? any help will be appreciated much! > Sincerely Barrow In[1]:= expression = x + 2x*y - x*y*z + u*x*y + 3u^2; In[2]:= Select[expression, MatchQ[#, c_.*x*y]&] Out[2]= 2 x y + u x y - x y z In[3]:= List@@% Out[3]= {2 x y, u x y, -(x y z)} Bhuvanesh, Wolfram Research