If you need to solve systems of non-linear equations, I'd say your options are pretty limited. Look around at commercial mathematics packages, I doubt that many will claim to be able to solve such systems. Most systems of non-linear equations have no solution(s) and even when they do the solution(s) are difficult to find. If you can approximate your equations with linear ones, then you have a good chance of solving that system (however the approximations will have to be pretty good). If you are stuck with non-linear equations, then an iterative method is probably your best chance.

If you can post your equations or send them to me, I might be able to give you some more help.

Cowski Continued...

And if iteration is your best chance then it is not that hard to setup a newton rhapson loop of the DO WHILE type in a program such as Visual Basic..

Will try to find the code for my thesis for you.. Keep you posted..

Cheers

Please don't misunderstand my previous post. I did not intend to make it sound impossible to program the Newton-Raphson method in VB, in fact it would be fairly simple to do so. My point is, systems of nonlinear equations are intrinsically a difficult problem to obtain solutions for. Obtaining a solution will require pretty good initial guesses, and even then there are no guarantees.

BTW, you can find source code for Newton-Raphson (in FORTRAN or C++) at www.nr.com.