Multiplying large polynomials
- To: mathgroup at smc.vnet.net
- Subject: [mg14685] Multiplying large polynomials
- From: Thomas Bell <tombell at stanford.edu>
- Date: Sun, 8 Nov 1998 21:15:43 -0500
- Sender: owner-wri-mathgroup at wolfram.com
I'm trying to multiply two huge polynomials, and memory is a major concern. I want to truncate the resulting polynomial to a specified power (N) in one of the variables (h), and I was wondering if it was possible to tell Mathematica to not bother multiplying two terms if the resulting power of h was greater than N. This is, of course, in the hope that this "automatic truncation" would save time and memory. For example, if poly1 = a h^2 + b; poly2 = d h + e; N = 2; then I would like to result to be result = a e h^2 + b d h + b e Instead, I have to write result = Expand[poly1 poly2]/.h^3 -> 0; which forces Mathematica to create the enormous product before truncating. Please cc to tombell at stanford.edu, and thanks in advance for any suggestions.