Solving system of ODE using rkfixed

[woeiken]

I have a system of ODE. There are 6 unknowns (4 second derivative, and 2 first derivative), and 6 equations.

In each differential equation, that particular unknwon is a function of 5 other unknowns, all to their highest order of derivatives.

My experience on MATHCAD is limited, but based on what I know, this creates a very problematic situation. When I tried to construct the D(t,X) function, I am really having tough time rearranging each differential equation such that the highest derivative of the remaining 5 unknowns do not appear in each differential equation. I don't think I can ever achive that goal. Each differential equation is so complex that the MATHCAD (version 2001) can't even show the complete symbolic term because it is way too large.

So my problem is like this: having such a system of ODE, where each differential equation is a function of the remaining unknowns to their highest derivative, how would I construct the D(t,X) function?

 

[IRstuff]

You might want to search the Mathcad collaboratory website and/or post your question there. There have been several postings on using RKFIXED there:

http://collab.mathsoft.com/~Mathcad2000

TTFN