Posted by J Hienola on February 24, 1998 at 11:10:40:

I would like to have some advices what would be a

relatively accurate and fast method to integrate

a stiff set of hundreds, even thousand, 1st order ODE's.

I have tried several different routines available on

net as a freeware and also some commercial NAG and

IMSL routines, such as semi-implicit Rosenbrock

method, and semi-implicit extrapolation method

(extremely slow), and some BDF routines (quite a fast,

commercial). Problem is that I can't calculate

Jacobian matrix of the set of my equations explicitely.

Therefore I would like to hear, if anybody knows a

good way to solve my problem. I'm using Fortran 90

language on a single processor machine, and I really

would like some uncommercial method.