[petsc-users] MATBDIAG in > 3.1

[Matthew Knepley]

You can get this effect using PCBJACOBI, setting the number of local
blocks, and using -sub_pc_type lu -sub_ksp_type preonly.

   Matt

On Thu, Dec 1, 2011 at 4:28 AM, Parker, Andrew (UK Filton) <
Andrew.Parker2 at baesystems.com> wrote:

> Hi,****
>
> ** **
>
> I’ve been using PETSc for a conventional full parallel implicit solver,
> currently in MPIBAIJ format.  However, I’d like to understand the
> performance verse memory and speed trade-offs of just having a block
> diagonal system.  In this case I do not scatter to the off diagonal
> blocks.  Each block is 7x7 in size and fully dense.  In my view this should
> be a point implicit solution of the system.  I am looking for the best way
> to solve this in PETSc, clearly because of the lack of coupling between
> neighbouring cells by only having a block diagonal it’s actually a 7x7
> dense linear solve, but to test my theory at present I’d prefer to just not
> scatter to off diagonals, and use:****
>
> ** **
>
> MATBDIAG with my current ksp solver and take it from there.  BDIAG seems
> to have been removed as off 3.0:****
>
> ** **
>
> http://www.mcs.anl.gov/petsc/documentation/changes/300.html****
>
> ** **
>
> Can anybody help me with this, your thoughts on the above and what I
> should use to solve this reduced system would be appreciated??****
>
>
> Cheers,****
>
> Andy****
>
> ********************************************************************
> This email and any attachments are confidential to the intended
> recipient and may also be privileged. If you are not the intended
> recipient please delete it from your system and notify the sender.
> You should not copy it or use it for any purpose nor disclose or
> distribute its contents to any other person.
> ********************************************************************
>
>


-- 
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-users/attachments/20111201/01fa51b5/attachment.htm>