numerical solutions to matrices??

*To*: mathgroup at smc.vnet.net*Subject*: [mg2761] numerical solutions to matrices??*From*: Clark Snowdall <snowdall at rodin.colorado.edu>*Date*: Wed, 13 Dec 1995 02:02:51 -0500*Organization*: University of Colorado

I'm in a bit of a jam. I have a system: phi'[t] == A.phi[t] that I have to numerically solve. Both A and phi[t] are 18x18 matrices, A is composed completely of real numbers (mainly zeros), and I need to solve it for phi at various times and for various initial conditions for phi. I tried the Runge-Kutta programming example that came with my version of Mathematica and while it worked for 4x4 matrices it choked on an 18x18. It's needed for an orbit determination program that I am writing (in a desparate effort to pass a class). If anyone knows how to solve a problem like this OR knows anything about orbit dtermination using Mathematica I would VERY much appreciate it. Thanks!!