TS_RK enhancements

[Kai Germaschewski]

Forget about the part below, btw. Clearly, in many cases for the implicit
methods it is necessary to preserve the solution at the previous time until
we're done finding the new solution.

--Kai


On Sat, May 16, 2009 at 12:07 AM, Kai Germaschewski <
kai.germaschewski at unh.edu> wrote:


> Obviously for methods where steps may fail and will be retried, it's
> necessary to preserve the old solution, however
> many schemes just call KSPSolve(.., update) or SNESSolve(..., update). In a
> linear method, I suppose by definition the operator does not depend on the
> current "sol". In a nonlinear problem, it will, however I suppose that
> SNESSolve() wouldn't update the solution vector until the very end, or am I
> missing something?
>
> Point being, all these VecCopy()'s aren't really necessary and actually end
> up making the code a bit more complicated than needs be, and obviously
> aren't helping performance. (For implicit methods, those copies will
> generally be negligible, but for the explicit ones (euler eg), that's not so
> clear...)
>
> --Kai
>
> --
> Kai Germaschewski
> Assistant Professor, Dept of Physics / Space Science Center
> University of New Hampshire, Durham, NH 03824
> office: Morse Hall 245F
> phone:  +1-603-862-2912
> fax: +1-603-862-2771
>
>


-- 
Kai Germaschewski
Assistant Professor, Dept of Physics / Space Science Center
University of New Hampshire, Durham, NH 03824
office: Morse Hall 245F
phone:  +1-603-862-2912
fax: +1-603-862-2771
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