[petsc-dev] VecGetSubVector() outupt

[Sander Arens]

>
> Or VecGetSubVectorDM(vec,PetscInt numfields,PetscInt *fields,&subvec)? The
> problem with this one is each new call has to create a new subdm unless we
> stash it in the DM.

 I also don't like the name for this one as it doesn't have any DM in its
arguments, while VecGetSubVectorDM(vec,subdm,&subvec) or DMCreateSubDM() do.

On 7 November 2016 at 17:56, Barry Smith <bsmith at mcs.anl.gov> wrote:

>
>    So something like VecGetSubVectorDM(vec,subdm,&subvec)? I hate having
> so many functions but don't see how to avoid it. Or
>
> VecGetSubVectorDM(vec,PetscInt numfields,PetscInt *fields,&subvec)?   The
> problem with this one is each new call has to create a new subdm unless we
> stash it in the DM.
>
>
>
>
> > On Nov 7, 2016, at 6:17 AM, Matthew Knepley <knepley at gmail.com> wrote:
> >
> > The way we have chosen to manage Vec output is to override the VecView
> function with DM-specific output functions. This strategy is currently
> broken for VecGetSubVector().
> >
> > Really what we want is for the Vec to have the correct subdm if indeed
> it is a subfield. However, its possible that the IS is some random thing,
> like points intersecting some surface, so we don't want it to blindly copy
> over the function pointers.
> >
> > How about we supplement DMCreateSubDM() with VecGetSubvectorDM(), which
> calls it underneath and sets up the vector correctly?
> >
> >    Matt
> >
> > --
> > 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
>
>
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