A different kind of lagged preconditioner

Matthew Knepley knepley at gmail.com
Mon Mar 23 14:16:54 CDT 2009

On Mon, Mar 23, 2009 at 2:06 PM, Rafael Santos Coelho <
rafaelsantoscoelho at gmail.com> wrote:

> Barry,
> sorry if I'm coming off stubborn or something, but I think I'm not
> following your reasoning.
>  NO.
>>  If you are using LU to construct a preconditioner then you ARE providing
>> the Jacobian explicitly (as a sparse) matrix.  Each time the preconditioner
>> is built this sparse matrix is factored.
> What do you mean by "providing the jacobian explicity (as a sparse)
> matrix"? I thought that there was no explicit jacobian matrix, but only a
> MATMFFD context.

If there is no matrix, what are you factoring?


> Rafael
What most experimenters take for granted before they begin their experiments
is infinitely more interesting than any results to which their experiments
-- Norbert Wiener
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20090323/06e0f582/attachment.htm>

More information about the petsc-users mailing list