Re: Implementing hybrid explicit/implicit ODE stepper

[Tuomo Keskitalo <Tuomo dot Keskitalo at iki dot fi>]

On 06/04/2009 08:40 PM, Rhys Ulerich wrote:

> This integrator tends to get used in DNS of Navier-Stokes since the
> memory savings become significant for very large fields.

Ok, now I understand a bit more. I don't think the current GSL 
ode-initval is directly suitable for that kind of specialized problem. 
The framework does not support separation of f(u) into two components. 
You would first have to make changes to gsl_odeiv_system to provide 
that, and then modify all the rest accordingly. Might be doable, I don't 
know.

Would your application benefit from step size control, or evolution 
functionality similar to those in ode-initval? If yes, then you might 
try to start from ode-initval and modify it. Otherwise I suggest you 
look for how others have designed these kinds of solvers and then create 
a new framework suitable for this kind of a problem.

Of course, if you end up implementing only that one stepper, you can use 
code snippets from ode-initval for it.

Regards,
Tuomo

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