Hello, I have a question regarding ODE steppers. I would like to integrate a stiff system, and obtain output which is fine grained where needed and has bold time steps where the trajectory is more flat. This is ideal for plotting the result I think, and gives me some insight into which step sizes the integrator thought reasonable.
So, I wanted to try to use the low-level evolve_apply functions (is that the right way to go about this?). But the really good solvers for stiff problems require a driver object, which allocates all of the arguments for the evolve_apply function internally. I don't see any way to access those objects. So, I don't know how to call the evolve_apply function at all, other than making those objects a second time (manually) and hoping that they are similar enough (i.e. that I don't specify two very different control functions by accident). It just seems unatural to have the driver internal step/control function and another (manually made) step/control function. Should I... not try to obtain adaptively spaced output and just pick a fixed time-step for the trajectory? (this is what I'm doing now) This would probably mean that I won't know which steps the solver made. Currently I pick a safe (small) step size so that the plotted curves look smooth enough. I suspect that I don't fully understand the reasoning behind the odeiv2 interface. Best, Andrei Kramer