I would like to use Runge-Kutta 8th order method (89) in a celestial mechanics / astrodynamics application, written in C++, using a Windows machine. Therefore I wonder if anyone knows a good library / implementation that is documented and free to use ? It is ok if it is written in C, as long as there aren't any compilation problems to be expected.
So far I have found this library ( mymathlib ). The code seems ok, but I haven't found any information on licensing.
Can you help me by revealing some of the alternatives you might know and would suit my problem ?
I see that there aren't really that many C/C++ source codes available as I expected. Therefore a Matlab/Octave version would be ok too (still has to be free to use).