Problem with MatMatMultTranspose

[Matthew Knepley]

On Fri, Sep 18, 2009 at 7:32 AM, Niall Moran <nmoran at thphys.nuim.ie> wrote:

> Matthew Knepley wrote:
>
>> On Thu, Sep 17, 2009 at 12:44 PM, Niall Moran <nmoran at thphys.nuim.ie<mailto:
>> nmoran at thphys.nuim.ie>> wrote:
>>
>>    Hi,
>>
>>    I am just wondering if anything has changed on the status of this
>>    feature. Would be great to be able to perform matrix vector
>>    multiplications on complex Hermitian matrices by only providing
>>    one half of the matrix.
>>
>>
>> It is not curently in the todo list since we have only had one request. It
>> seems like it would just take being careful about the
>> complex case for SBAIJ if you would like the try the implementation. We
>> can answer questions.
>>
>>  Thanks for you rapid response. I would be interested in attempting to
> implement this for MPIAIJ if it would not be too involved. Would you be able
> to sketch a rough outline of what this would involve? Would I need to just
> modify the MatMult_MPIAIJ function or would I need to modify the creation of
> the scatterers in MatAssemblyBegin_MPIAIJ?
>
> Could anyone suggest some documentation that describes how the matrix
> vector multiplication works in petsc for MPIAIJ typed matrices?
>
> Does matrix vector multiplication with just the upper half work for real
> symmetric matrices?
>

1) Understand the SBAIJ implementation. This is used for real symmetric
matrices

2) In the places where the lower triangle is retrieved, add a complex
conjugation.

  Matt


> Regards,
>
> Niall.
>
-- 
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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