numerical integration problem

*To*: mathgroup at smc.vnet.net*Subject*: [mg77818] numerical integration problem*From*: Sean <sshiau2 at wisc.edu>*Date*: Sun, 17 Jun 2007 06:12:04 -0400 (EDT)

Hi, I know that to post a technical question here, it is best to give an example. But my program is huge but straightforward, so I hope to make clear my problem by simply describing how I design the program. My problem at hand is that I have a list of linearly coupled equations whose coefficients are normal functions of some parameters. for a simple example x*f[w]+y*g[w]=z[w]; x*b[w]+y*m[w]=n[w]; I need to solve for x and y. Of course, the naive way is to put these equations into a matrix and solve for x and y----remember my problem has a 20 X 20 matrix. After this, x and y are expressed in terms of these functions. I just defind them as x[w_]:=...; y[w_]:=...; Now I need to do a numerical integration over these functions x[w], and y[w].. But the trouble comes. Because of these huge expressions for the target functions x[w] and y[w], my dram is immediately eaten up and mathematica automatically terminates the program... I read in a previous post that suggests if I redefine x[w_?NumerQ];= ... ; y[w_?NumerQ]:=...; Would this help, or there is a smarter way of fomulating my problem so that it would run faster and use less memory. Your help is greatly appreciated, Sean