Re: How to select terms wanted in a series

*To*: mathgroup at smc.vnet.net*Subject*: [mg85957] Re: [mg85916] How to select terms wanted in a series*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Thu, 28 Feb 2008 02:59:25 -0500 (EST)*Reply-to*: hanlonr at cox.net

Cases[expression, x*y*_.] Bob Hanlon ---- Barrow <GRseminar 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 >