[petsc-users] Compute C*Ct using MatCreateTranspose for Ct

[Matthew Knepley]

On Thu, Sep 24, 2020 at 6:48 AM Mark Adams <mfadams at lbl.gov> wrote:

>
>> Is there a way to avoid the explicit transposition of the matrix?
>>
>
> It does not look like we have A*B^T for mpiaij as the error message says.
> I am not finding it in the code.
>
> Note, MatMatMult with a transpose shell matrix, I suspect that it does an
> explicit transpose internally, or it could notice that you have C^T*C and
> we might have that implemented in-place (I doubt it, but it would be legal
> and fine to do).
>

We definitely have


https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Mat/MatPtAP.html

For now, you can put the identity in for A. It would be nice it we assumed
that when A = NULL.

Patrick, the implementation strategy is broken for the MatProduct mechanism
that was just introduced, so
we cannot see which things are implemented in the documentation. How would
I go about fixing it?

  Thanks,

     Matt


> Many thanks,
>> Olivier Jamond
>>
>>
>>

-- 
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

https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>
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