[petsc-users] BiCGSTAB for general use

[Jed Brown]

On Mon, Aug 22, 2011 at 05:51, Paul Anton Letnes <
paul.anton.letnes at gmail.com> wrote:

> Not that I know of. The operator contains integrals over a stochastically
> rough surface. Due to its random nature, any sparsity structure will depend
> on each surface realization,
>

Are you integrating the probability density or just a single realization?
Integrating over the stochastic dimensions may preserve more structure.


> > Your independent variables discretize a 2D space of angles, right? Then
> try a 2D color plot.
>
> Sort of. That may be a good idea. Perhaps we could use something like that
> to learn more about the physics anyway.
>

At this point, I would hope that this gives some insight into structure that
can be used to build a better solver.

I have so far not plotted or analyzed any singular vectors or eigenvectors.
> To simulate a physically meaningful system will probably take quite a few
> CPU hours... I attach a plot of singular values for a small (4608x4608) test
> matrix. It does not look too great at first glance.
>
> The largest singular value is 20107, the smallest 69.7, giving a ratio of
> 288 or so.
>

I don't see any obvious useful structure here.
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