[petsc-dev] spectral deferred correction (SDC) time stepper

[Barry Smith]

On May 29, 2013, at 3:44 PM, Matthew Emmett <memmett at gmail.com> wrote:

> On Wed, May 29, 2013 at 1:37 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote:
> Matthew Emmett <memmett at gmail.com> writes:
> > Ideally I think it would be nice if the user could just add "-ts_type sdc"
> > and have the code figure out which SDC variant (explicit, implicit, or
> > imex) to use.  The trouble I am having is that a users RHSFunction can be
> > recast into implicit form by TSComputeIFunction if an implicit time-stepper
> > is used... which means that I can't just check whether RHSFunction has been
> > registered to switch between explicit only and implicit only.
> 
> TSGetRHSFunction() should return NULL if the user did not set an
> RHSFunction, however, many stiff systems are described using RHSFunction
> as a matter of convenience, and because in some parameter regimes, they
> may be non-stiff.
> 
> OK, understood.
>  
> > Is there a preferred way of doing this, or should I add another option
> > to select which SDC variant to use?
> 
> I would use an option for this.  The user likely wants to try both for
> moderately stiff systems.
> 
> If you would like comments on your code and general approach, please
> push it in a fork on bitbucket or github.
> 
> Will do -- I will tidy up a few things and make the history a bit more sane first.

   A programmer after Jed's heart :-). Welcome to the club Matt, glad to have you aboard.

   Barry


> 
> Thanks for your comments,
> Matt 
>