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Re: Coefficient in multivariate series

  • To: mathgroup at
  • Subject: [mg3611] Re: Coefficient in multivariate series
  • From: pecora at (Louis M. Pecora)
  • Date: Thu, 28 Mar 1996 00:10:24 -0500
  • Organization: Naval Research Laboratory
  • Sender: owner-wri-mathgroup at

In article <4j7gsa$af4 at>, Harald Berndt
<haraldb at> wrote:

> Samuel Bengmark wrote:
> > 
> > I wonder if anyone out there knows how to get mathematica
> > to extract a coefficient of a monomial in a multivariate to
> > series or polynomial. For example how do I get mathematica to
> > give me the coefficient of x*y*z^3 in (1+x+y)^2*(2+y)*(5+z)^4.
> It's not very elegant, but I could'n get any simpler forms to work ... 
> This will do it for you:
> First[
>         Select[t,
>         (MemberQ[#, x] && MemberQ[#, y] && MemberQ[#, Power[z, 3]])& ]
> ]

Hmmm...dumb question:

Why wouldn't

First[ Select[t, (MemberQ[#, x*y*z^2])& ] ]

work?  I'm probably missing something here.

Louis M. Pecora
pecora at

/* My views and opinions are not those of the U.S. Navy.
   If you want those, you have to start a war.  */


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