[petsc-dev] attaching field information to PetscLayout?

[Jed Brown]

On Sat, May 14, 2011 at 22:26, Dmitry Karpeev <karpeev at mcs.anl.gov> wrote:

> So the splits are identified by the IS (e.g., "give me the subvec
> corresponding to the split with this IS")?
>

Yes, that is VecGetSubVector(Vec,IS,Vec*).


> I assume that will require IS matching.  Is that faster than string
> matching (I guess it depends on the string/IS length/type).
>

That depends on the Vec implementation and IS. I think there are many places
where we would like IS matching (all the submatrix stuff, for example). IS
is (almost) immutable at this point, therefore we can create a unique token
for each IS. Then looking up an IS becomes a single hash lookup.
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