Re: Multiplying Polynomials
- To: mathgroup at smc.vnet.net
- Subject: [mg117911] Re: Multiplying Polynomials
- From: TBone at giganews.com
- Date: Mon, 4 Apr 2011 06:29:37 -0400 (EDT)
- References: <in6kh7$2iu$1@smc.vnet.net> <in86kl$9un$1@smc.vnet.net>
On 2011-04-02 17:06:13 -0500, Daniel Lichtblau said: > ----- Original Message ----- >> From: "TBone" <TBone at yahoo.com> >> To: mathgroup at smc.vnet.net >> Sent: Saturday, April 2, 2011 2:41:16 AM >> Subject: Multiplying Polynomials >> This is very simple and I freely confess my ingnorance. >> >> I'm trying to set up a generating function to count some letters of >> the >> alphabet. Specifically, I need to multiply two polynomials in the >> variable x, do some surgery on the result, and continue with another >> letter. >> >> Here is my problem. >> >> I start with: >> >> expand[(1+ax+a^2x^2+...)*(1+bx+b^2x^2+...)] >> >> and continue with: >> >> expand[(1+ax+bx+abx^2+...)*(1+cx+c^2x^2+...)] >> >> Howerver, it chokes on the following: >> >> expand[(1 + a x + b x + c x + a^2 x^2 + a b x^2 + b^2 x^2 + a c x^2 + >> b >> c x^2 + >> c^2 x^2 + a^2 b x^3 + a b^2 x^3 + a^2 c x^3 + a b c x^3 + b^2 c x^3 + >> a c^2 x^3 + b c^2 x^3 + a^2 b^2 x^4 + a^2 b c x^4 + a b^2 c x^4 + >> a^2 c^2 x^4 + a b c^2 x^4 + b^2 c^2 x^4 + a^2 b^2 c x^5 + a^2 b c^2 >> x^5 + >> a b^2 c^2 x^5 + a^2 b^2 c^2 x^6)*(1 + dx + d^2 x^2)] >> >> What gives? >> >> TIA!! >> >> --TB > > Dunno, from this description. No idea what you expected. ^^^^^^^^^^^^^^^^^^^^^^^^^ I guess I expected the Free-Form Input to figure out what was needed. It seems to work magically. :) Using "Expand" and a different grouping of coefficients works. Thanks for the help everyone! --TB > > > Daniel Lichtblau > Wolfram Research