Hi all
I'm in the process of coding an adaptive step-size Runge-Kutta method in C to
solve some equations related to my research, but I'm seriously considering
switching to GSL to avoid reinventing the wheel (and because my code is far
from optimal). My main issue at the moment, looking at the example at
https://www.gnu.org/software/gsl/manual/html_node/ODE-Example-programs.html, is
that I am not sure how to adapt this to integrate BACK from an initial value.
I.e, for a 2 dim. 1st order system with initial values given at a point away
from the origin (on the positive real axis), how do I get the solver to take
negative steps BACK to the origin? I would appreciate some help with this, an
illustration in
terms of the example would be perfect (or a nudge in the right direction). As
far as I can determine I need to modify the call to the evolution routine in
some way, but I find the documentation difficult to follow.
Regards
Martin