[petsc-dev] Stokes and saddle point solvers in PETSc?

[Barry Smith]

On Jun 14, 2011, at 8:36 PM, Matthew Knepley wrote:

> On Wed, Jun 15, 2011 at 1:20 AM, Barry Smith <bsmith at mcs.anl.gov> wrote:
> 
> On Jun 14, 2011, at 7:59 PM, Jed Brown wrote:
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> > On Wed, Jun 15, 2011 at 02:53, Barry Smith <bsmith at mcs.anl.gov> wrote:
> >  It seems we should provide a DMSDA that is built specifically for staggered grids, with the correct number of "slots" in the correct "locations", it would have appropriate grid hierarchies and interpolation/restriction. Not terribly hard but a bit of basic plumbing code. I would rather have this then try to "tack on" the current DA a bunch more stuff.
> >
> > Yeah, though there are many different staggered discretizations so this could end up being a big project. Not conceptually hard, just a lot of code. DMDA is already not especially small.
> 
>  DMDA started out small. DMSDA will start out small :-)
> 
>  Actually before we do DMSDA we probably should do a code review of DM, then of DMDA and slim down DMDA a good amount.
> 
> My vote would be to layer PetscSection on top of DMDA. That would allow arbitrarily complex data layout over a dead simple
> topology. Its halfway to DMMesh, and it should be the easy half.

  It won't give the proper layout of degree's of freedom relative to their neighbors of the stagger mesh nor communicate the right ghost points. 

   Barry

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>    Matt
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>   Barry
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> -- 
> What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.
> -- Norbert Wiener