RE: Simplifying the *Individual Coefficients* in Series Expansions?

*To*: mathgroup at smc.vnet.net*Subject*: [mg35232] RE: [mg35214] Simplifying the *Individual Coefficients* in Series Expansions?*From*: "David Park" <djmp at earthlink.net>*Date*: Wed, 3 Jul 2002 05:13:46 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

Try using the third form of Collect with h = Simplify. David Park djmp at earthlink.net http://home.earthlink.net/~djmp/ > From: AES [mailto:siegman at stanford.edu] To: mathgroup at smc.vnet.net > > 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? >