[petsc-dev] FieldSplit fixes in 3.3

Matthew Knepley knepley at gmail.com
Sun Aug 19 09:06:36 CDT 2012

On Sun, Aug 19, 2012 at 2:31 AM, Dmitry Karpeev <karpeev at mcs.anl.gov> wrote:

> I just pushed a couple of fixes to PCFIELDSPLIT in petsc-3.3 (
> http://petsc.cs.iit.edu/petsc/releases/petsc-3.3/rev/943dde820f7f,
> http://petsc.cs.iit.edu/petsc/releases/petsc-3.3/rev/5a9ebf885615)  In
> particular, the second changeset
> modifies the way the splits' nullspaces are configured.  In my view the
> old behavior was not quite correct.
> Here are the relevant comments:
> http://petsc.cs.iit.edu/petsc/releases/petsc-3.3/rev/5a9ebf885615#l1.9
> and
> http://petsc.cs.iit.edu/petsc/releases/petsc-3.3/rev/5a9ebf885615#l1.37
> However, I don't have use cases where the old way of handling block
> nullspaces
> leads to a failure.  If there is justifiable legitimate usage for the old
> ways, the
> changeset can be easily backed out.

1) I fixed the Schur prefixes in dev, so do not merge this over it

2) It was my understanding that the Schur nullspace should be attached to
A_11, but
    if we want to find another way to do it, that is fine.


> Dmitry.
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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