[petsc-dev] Vector operations on ghosted vectors

[John Mousel]

I use the data in the vectors for things besides pure vector operations. In
the context of a sub-iteration scheme for an incompressible solver, I want
to use the values stored in the vector at the previous iteration to
construction the non-linear term. This requires copying not just the local
portion of the vector in the u(k)->u(k-1) operation, but the ghosts as
well. Doesn't copying the entire ghosted vector make sense in this context?

John


On Fri, Mar 1, 2013 at 8:09 AM, Jed Brown <jedbrown at mcs.anl.gov> wrote:

> On Wed, Feb 27, 2013 at 4:56 PM, John Mousel <john.mousel at gmail.com>wrote:
>
>> Is there a possibility of adding a wrapper function around a few basic
>> vector operations such as VecCopy, VecAXPY, VECAXPYPZ... to operate on
>> ghosted vectors? I perform a lot of vector operations including the ghost
>> region to avoid communication.
>>
>
> Can you explain the context where operating with local forms in this way
> makes sense? Usually you would either be working locally, in which case you
> copy between local forms (or purely local work vectors) or you are
> operating globally in which case there is nothing to gain by applying
> operations to the local form.
>
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