Simplifying the *Individual Coefficients* in Series Expansions?

*To*: mathgroup at smc.vnet.net*Subject*: [mg35214] Simplifying the *Individual Coefficients* in Series Expansions?*From*: AES <siegman at stanford.edu>*Date*: Tue, 2 Jul 2002 02:12:46 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

I have a long expression f that involves integers times various powers of symbols b and x, i.e. f = ratio of two lengthy polynomials in b and x If I series expand this in x , viz. fS = Series[f, {x, 0, 2}] // Normal I get an answer in the form fS = c1 x + c2 x^2 where the coefficients c1 and c2 in the resulting series expansion come out as rather messy expressions (ratios of polynomials). In my problem, however, these coefficients actually happen to simplify substantially (since there are common factors in their numerators and denominators), and I'd like to have them in simplified form. But if I write fS // Simplify I'm back in lengthy polynomial form; and if I try something like fS = (Coefficient[fS, x] // Simplify) x + (Coefficient[fS, x^2] // Simplify) x^2 I get an expression that looks great, but will not evaluate numerically. Any easy way around this?

**Follow-Ups**:**Re: Simplifying the *Individual Coefficients* in Series Expansions?***From:*Daniel Lichtblau <danl@wolfram.com>