I have not, since it is much simpler to add 6 pragmas to the loops of
rk45_apply to achieve the same goal.
I suspect, from glancing at the first example at
http://www.gnu.org/software/gsl/manual/html_node/ODE-Example-programs.html,
you could achieve parallelization atop stock GSL builds with fewer
than 6 pragmas.
I also suspect that by using OpenMP tasks over the coarser granularity
concept (1 ODE) instead of the parallel-fors over the finer
granularity method (1 step) you may see better overall performance.
- Rhys