[petsc-users] How to compute RARt with A and R as distributed (MPI) matrices ?

[Franck Houssen]

I read the doc, and googled this before to write a dummy example. So, matRARt is only for sequential matrices, and, matPtAP for distributed ones : correct ? (means, I "just" used the "wrong" method) 
If so, this is a major difference which does not seem (to me) to be emphasized enough in the doc, in particular for a new user (the matRARt and matPtAP pages are the same with R replaced with Pt). Where was it possible to find this information ? 

Franck 

----- Mail original -----

> De: "Dave May" <dave.mayhem23 at gmail.com>
> À: "Franck Houssen" <franck.houssen at inria.fr>, "PETSc users list"
> <petsc-users at mcs.anl.gov>, "petsc-dev" <petsc-dev at mcs.anl.gov>
> Envoyé: Mercredi 21 Juin 2017 15:11:27
> Objet: Re: [petsc-users] How to compute RARt with A and R as distributed
> (MPI) matrices ?

> You can assemble R^t and then use MatPtAP which supports MPIAIJ

> On Wed, 21 Jun 2017 at 15:00, Franck Houssen < franck.houssen at inria.fr >
> wrote:

> > How to compute RARt with A and R as distributed (MPI) matrices ?
> 

> > This works with sequential matrices.
> 
> > The doc say "currently only implemented for pairs of AIJ matrices and
> > classes
> > which inherit from AIJ": I supposed that MPIAIJ was someway inheriting from
> > AIJ, seems that it doesn't.
> 

> > Is this kind of matrix product possible with distributed matrices in PETSc
> > ?
> > Or is this a known limitation ?
> 
> > Do I go the wrong way to do that (= should use another method) ? If yes,
> > what
> > is the correct one ?
> 

> > Franck
> 

> > PS: running debian/testing + gcc-6.3 + bitbucket petsc.
> 

> > >> mpirun -n 2 matRARt.exe seq
> 
> > Mat Object: 1 MPI processes
> 
> > type: seqaij
> 
> > row 0: (0, 1.) (1, 0.)
> 
> > row 1: (0, 0.) (1, 1.)
> 

> > >> mpirun -n 2 matRARt.exe mpi
> 
> > [0]PETSC ERROR: --------------------- Error Message
> > --------------------------------------------------------------
> 
> > [0]PETSC ERROR: No support for this operation for this object type
> 
> > [0]PETSC ERROR: Matrix of type <mpiaij> does not support RARt
> 
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