[petsc-users] Diagnosing Poisson Solver Behavior

[Matthew Knepley]

On Thu, Oct 15, 2015 at 12:10 PM, K. N. Ramachandran <knram06 at gmail.com>
wrote:

> Hello Matt,
>
> On Thu, Oct 15, 2015 at 12:18 PM, Matthew Knepley <knepley at gmail.com>
> wrote:
>
>>
>> The bad design decision is using a storage format designed for high speed
>> MatMult() to use for data interchange. You should be
>> using the API for value insertion rather than some storage format.
>>
>
> Ok, noted. Instead of using CreateMatSeqAIJWithArrays, I have also tried
> setting up the Mat passed into the ComputeMatrix function, using
> MatSetValue where the cols and values are referred to values in the CSR
> format, but I still get the same error. It looks like the Mat is not
> preallocated properly in the DM, even when I use DMDACreate3d.
>

Another explanation is that the matrix is preallocated correctly, but you
are mapping the row and columns indices differently than the
DM. This what I was refering to when I said that getting the parallel
partition correct would be challenging.

  Matt


> Could you suggest what I can do to resolve this?
>
> Thanks,
> K.N.Ramachandran
> Ph: 814-441-4279
>



-- 
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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