On Thu, Dec 29, 2011 at 11:01 AM, Dave Nystrom <dnystrom1 at comcast.net>wrote:
> I have recently added the capability to have a separate preconditioning > matrix in the petsc interface for the code I am working with. I have two > types of preconditioning matrices that I have questions about. One is > tridiagonal and the other is 7 diagonals. In both cases, the the diagonals > are all lexically adjacent. Or phrased differently, the tridiagonal matrix > has a bandwidth of 3 and the 7 diagonal matrix has a bandwidth of 7 and so > they are compact or dense band systems. > > I was wondering what petsc ilu will do for preconditioning matrices like > these. Will it produce an exact lu factorization or a nearly exact > factorization? I'm interested in the answer to this question because I am > thinking I might be able to run this preconditioner on the gpu using the > txpetscgpu package. > If you are running ILU(0), it has exactly the same nonzero pattern. The convergence is unpredictably. I would consult Yousef Saad's book for further information. Matt > Thanks, > > Dave > -- 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 -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-dev/attachments/20111229/a01c2335/attachment.html>
