[petsc-users] Diagnosing Poisson Solver Behavior

[K. N. Ramachandran]

Hello Matt,

Thanks for your reply. I am actually retrying against the latest PETSc and
will revert once I get the information.

On Mon, Oct 12, 2015 at 9:39 AM, Matthew Knepley <knepley at gmail.com> wrote:

> On Sat, Oct 10, 2015 at 7:56 PM, K. N. Ramachandran <knram06 at gmail.com>
> wrote:
>
>> Sorry, some more questions.
>>
>> 3) Also, for Dirichlet bc, I specify the value through Identity rows,
>> i.e. A_ii = 1 and the rhs value would correspond to the Dirichlet
>> condition. I am specifying it this way for my convenience. I am aware that
>> MatZerosRowColumns might help here, but would keeping it this way be
>> detrimental?
>>
>
> That is fine. However you would want to scale these entries to be
> approximately the same size as the other diagonal entries.
>
>
>> 4) Can I expect symmetric matrices to perform better, i.e. if I eliminate
>> Dirichlet rows? But I would still be left with Neumann boundary conditions,
>> where I use the second order formulation. If I used the first order
>> formulation and made it symmetric, would that be an advantage? I tried the
>> latter, but I didn't see the condition number change much.
>>
>
> Will not matter for MG.
>
>     Matt
>
>
>>
>>

Regards,
K.N.Ramachandran
Ph: 814-441-4279
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20151012/9ea66a0d/attachment.html>