[R-sig-dyn-mod] compiled code for ode solvers

Hi, I have a rather complex reaction-transport model written in R and I
would like to convert it to FORTRAN or C to gain some speed. I have gone
through the various packages mentioned in recent discussions on how to use
compiled code. Most of the examples in the packages are simply and easy to
understand, but my ode model calls various functions at each time step. For
example at each time step I need to solve a root finding problem. I know
how to auto compile the root finding and the ode codes separately using
ccsolver or code, but I'm not sure how the compiled ode code should call
the root finding code. There are other functions written in R to be called
in the main ode code too. I appreciate any advice you offer.

Thanks!
Jianghui Du