[petsc-dev] Fwd: [mumps-dev] support for distributed right-hand vectors?

[Jack Poulson]

Hi Alexander,

On Tue, Nov 13, 2012 at 12:53 PM, Alexander Grayver <agrayver at gfz-potsdam.de
> wrote:

>
> Jack,
>
> Thanks for the comment.
>
> Could you comment on or give a reference to the blow up in memory one
> observes when running general purpose direct solvers in parallel?
>
>
People tend not to publish these types of negative results.


> P.S. Does Clique support pivoting?
>
>
Not yet. It is something that I will eventually make time for, but its
importance for solving indefinite equations is somewhat overblown. It is
surprisingly easy to directly solve many time-harmonic wave equations with
a Cholesky-like LDL^T factorization. In extreme cases, one can add a small
imaginary diagonal shift, chosen in the proper direction to damp
propagating waves (this depends upon your convention for time-dependence
for any radiating boundary conditions, e.g., exp(i w t) or exp(-i w t)) and
then wrap the solves in a few iterations of GMRES(k). This is often
referred to as iterative refinement.

I will likely implement a few more high-performance triangular solve
algorithms before I add support for pivoting.

Best,
Jack
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