[petsc-users] Advise on choice of iterative solver

[Matthew Knepley]

On Wed, Jun 8, 2011 at 7:34 AM, Klaus Zimmermann <
klaus.zimmermann at physik.uni-freiburg.de> wrote:

> Hi Jed, Hi Matthew,
>
> thanks for your quick responses!
>
> On 06/08/2011 02:23 PM, Jed Brown wrote:
> > On Wed, Jun 8, 2011 at 14:17, Matthew Knepley <knepley at gmail.com
> > <mailto:knepley at gmail.com>> wrote:
> >
> >     However, you might look at Elemental
> >     (http://code.google.com/p/elemental/) which solves the complex
> >     symmetric eigenproblem and is very scalable.
> >
> >
> > Note that Elemental is for dense systems.
> >
> >
> > To solve your problem, it's important to know where it came from. The
> > average number of nonzeros per row doesn't tell us anything about it's
> > mathematical structure which is needed to design a good solver.
>
> We are doing quantum mechanical ab initio calculations. The Matrix stems
> from a two particle Hamiltonian in a product basis. Thus we have basis
> vectors S_{nm}. The sparseness is now due to the fact that the matrix
> element <S_{nm}|H|S_{n'm'}> can only be non-zero if |n-n'|<4 and |m-m'|<4.
>
> Does this help or do you need more information? Like the matrix
> construction code?
>

This does not just sound sparse, it sounds banded. Is this true? If so, you
can use dense, banded solvers instead.

   Matt


> Thanks,
> Klaus
>
>
>


-- 
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
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