[petsc-dev] MatMatMult gives different results

[Hong Zhang]

MatMatMult() in petsc is not well-tested for complex - could be buggy.
Can you send us the matrices A and B in petsc binary format for
investigation?

Hong

On Mon, Feb 6, 2012 at 5:55 AM, Alexander Grayver
<agrayver at gfz-potsdam.de>wrote:

> Dear PETSc team,
>
> I try to use:
> call MatMatMult(A,B,MAT_INITIAL_**MATRIX,PETSC_DEFAULT_DOUBLE_**
> PRECISION,C,ierr);CHKERRQ(**ierr)
>
> Where both A and B are rectangular, but A is sparse and B is dense. Both
> are double complex and distributed.
> The product PETSc gives me contains some errors in some part of the matrix.
> I output A, B and C then computed product in matlab.
>
> Attached you see figure plotted as:
> imagesc(log10(abs(C-Cm)))
>
> Where Cm -- product computed in matlab.
>
> The pattern and amplitude vary depending on the number of cores I use.
> This picture is obtained for 48 cores (I've tried 12, 64 cores as well).
>
> Where should I look for possible explanation?
>
> --
> Regards,
> Alexander
>
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