Problem with MatMatMultTranspose

[Niall Moran]

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?

Regards,

Niall.