MathGroup Archive 2001

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Expansion Coefficients in Multivariate Series Expansions?


I don't see why Coefficient[] doesn't work?

In[1]:=
d = (a*x + b*y + c*z)^5
Out[1]=
(a*x + b*y + c*z)^5
In[2]:=
Coefficient[d, x^2*y^2*z]
Out[2]=
30*a^2*b^2*c
In[3]:=
Coefficient[d, x*y*z^3]
Out[3]=
20*a*b*c^3
In[4]:=
Coefficient[d, x*y^3*z]
Out[4]=
20*a*b^3*c

Unless, of course, I didn't quite get your question.

Tomas Garza
Mexico City
----- Original Message -----
From: "A. E. Siegman" <siegman at stanford.edu>
To: mathgroup at smc.vnet.net
Subject: [mg26603] [mg26579] Expansion Coefficients in Multivariate Series Expansions?


> Given an expression that is the sum of products of integer powers of
> three variables (say x,y,z) multiplied by numerical coefficients:
>
>    f = c000 + c100 x + c010 y + c001 z + c110 x y + c211 x^2 y z + . . .
>
> where the  cijk's are all real numbers, and f may or may not be in
> Normal (or other) form, how do I find the coefficient of a particular
> term, e.g. c100 for the x term (*not*  c1000 + c110 y), or  ckmn for the
> x^k y^m z^n term?
>
> Neither Coefficient nor SeriesCoefficient seems to do this -- and the
> SeriesCoefficient[expr, {n1,n2,n3,..}] syntax seems to be mentioned but
> neither explained or illustrated in the on-line Help.
>
> Thanks, siegman at stanford.edu
>



  • Prev by Date: Re: How to get the slope of a Interpolation[] function at a specified point?
  • Next by Date: Re: Sum of Squares
  • Previous by thread: Expansion Coefficients in Multivariate Series Expansions?
  • Next by thread: Re: Expansion Coefficients in Multivariate Series Expansions?