[Trilinos-Users] null space removal

Nico Schlömer nico.schloemer at ua.ac.be
Wed Sep 8 13:01:41 MDT 2010

Oh, and for your reference Pavel and Rich had a paper on the pure
Neumann problem a couple of years ago, see
<www.cs.sandia.gov/~pbboche/papers_pdf/2005SIREV.pdf>. Not sure how much
of this is actually implemented somewhere in Trilinos.


On Wed, 08 Sep 2010 12:53:14 -0600, "David Day" <dmday at sandia.gov>
> Chris and Mike,
> The problem arises in continuation problems.  It can be addressed
> using a projection.  Often the projection is oblique (unsymmetric),
> and may be unstable.  A much better solution is to instead constrain the
> Krylov supspace.  A description of how to do this is presented in
> HF Walker, An adaptation of Krylov subspace methods to path following
> problems, SIAM J. Sci. Comput. 21(3),1191-1198.
> There was once an implementation in Loca, but I do not know the
> details.  I'm happy to discuss this further, particularly offline.
> --David Day
> On Wed, 2010-09-08 at 12:07 -0600, Christopher K. Newman wrote:
>> Is there a way to automatically remove a known null space during an
>> iterative solve?  Dare I say, similar to KSPSetNullSpace in Petsc.  Or
>> is the preferred method user implementation of a projection operator?
>> Thanks,
>> Chris
>> --
>> Christopher K. Newman
>> Los Alamos National Laboratory, T-3     Email: cnewman at lanl.gov
>> PO Box 1663 MS B216                           Phone: 505 606 0647
>> Los Alamos, NM 87545                          Fax: 505 665 5926
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