ODEs: rk routing with derivs on rhs



In my further attempts to understand my differential equations, I
tried to use the "rk" routine. I used "? rk" to get info about it but
it seems that I am limited as follows.

The system is 2 coupled 2nd order ODEs. It's only second order in h,
therefore I need an expression for h', h'', and v' for the integrator
and h, h', v will be my solution variables.

i can write these equations semi-explicitly... 

h' depends on h, h'' v, v'
v' depends on h, h', h'', v
h'' depends on h h' v'

It seems as though the rk routine is not happy with this, preferring
the rhs to be free of all derivatives. (the error I get is something
about attempting to take derivative with respect to a number)

Am I missing something? Does maxima have another numerical integrator
that can handle this type of coupling by some iterative method?

Bloody ODEs :-)



-- 
Daniel Lakeland
dlakelan at street-artists.org
http://www.street-artists.org/~dlakelan