Speeding up Inverting matrices.

*To*: mathgroup at smc.vnet.net*Subject*: [mg23010] Speeding up Inverting matrices.*From*: David McGloin <dm11 at st-andrews.ac.uk>*Date*: Tue, 11 Apr 2000 23:18:28 -0400 (EDT)*Organization*: University Of St Andrews*Sender*: owner-wri-mathgroup at wolfram.com

I wish to solve the matrix equation Ax = b for x where A is a 24 x 24 matrix and x and b are column matrices. Most of the values in the matrix are numbers (and many are equal to zero), but one remains unevaluated i.e element [1,10] may be 160 + d, where d is unevaluated. Currently we're using the command: x = {Inverse [A]. b} this works fine for the smaller matrices we use (8 x 8 and 16 x 16) but the calculation has now be runing for over 2 days (the smaller matrices may take many minutes if not seconds). The program is running on a PII 350MHz with 64Mb of RAM. Does anyone have any ideas about how to optimise our calculation? Ultimately I want to extract arbitary elements of x and plot them against the unevaluated element. Thanks for any help! David -- *************************************** David McGloin Dept. of Physics Univ. of St. Andrews dm11 at st-and.ac.uk

**Follow-Ups**:**Re: Speeding up Inverting matrices.***From:*Daniel Lichtblau <danl@wolfram.com>