[petsc-users] Parallel matrix multiplication

[Matthew Knepley]

On Mon, Jul 17, 2023 at 2:22 PM Barry Smith <bsmith at petsc.dev> wrote:

>
>
>    https://petsc.org/release/manualpages/Mat/MatPtAP/  also note that
> PETSc has a large infrastructure for efficient ways to compute various
> matrix-matrix operations with a variety of algorithms that can be all
> accessed by starting with
> https://petsc.org/release/manualpages/Mat/MatProductCreate/
>
>
> On Jul 17, 2023, at 1:13 PM, Karthikeyan Chockalingam - STFC UKRI via
> petsc-users <petsc-users at mcs.anl.gov> wrote:
>
> Hello,
>
> I would like to perform the following operation
>
> [P^T A P] x’ = P^T f
>
> If P is thin, you might want to consider making a MatLRC and passing that
to a Krylov method, probably with a small precondition matrix (like P^T
diag(A) P).

  Thanks,

     Matt


> Where P is a rectangular matrix and A is a square matrix.  All the
> matrixes are constructed using MPIAIJ.
>
> Should I be concerned about the parallel partitioning of the matrix P and
> A?
>
> Or can I just go ahead and use MatMatMult to compute [P^T A P]?
>
> Is there any in-built functionality to perform this operation?
>
> Kind regards,
> Karthik.
>
>
>
>
>
>
>
> --
> *Dr. Karthik Chockalingam*
> High-Performance Software Engineer
> Hartree Centre | Science and Technology Facilities Council
> karthikeyan.chockalingam at stfc.ac.uk
>
>  <image001.png>
>
>
>

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