[petsc-users] reuse Mumps factorization for multiple RHS

Zhang, Hong hzhang at mcs.anl.gov
Tue Aug 4 21:28:23 CDT 2020

See case '"-num_rhs" in petsc/src/ksp/ksp/tests/ex30.c


From: petsc-users <petsc-users-bounces at mcs.anl.gov> on behalf of Matthew Knepley <knepley at gmail.com>
Sent: Tuesday, August 4, 2020 7:29 PM
To: Anthony Paul Haas <aph at email.arizona.edu>
Cc: petsc-users <petsc-users at mcs.anl.gov>
Subject: Re: [petsc-users] reuse Mumps factorization for multiple RHS

On Tue, Aug 4, 2020 at 7:57 PM Anthony Paul Haas <aph at email.arizona.edu<mailto:aph at email.arizona.edu>> wrote:

When using Mumps to solve a linear system of equations (see below), can I reuse the factorization to solve for multiple RHS, ie, can I use KSPSolve multiple times while only building a different RHS in between the calls to KSPSolve?

Yes. It should detect that you have not changed the operator for the KSP and thus not refactor the matrix.





call KSPSetType(self%ksp,KSPPREONLY,self%ierr_ps)

call KSPGetPC(self%ksp,pc,self%ierr_ps)

call PCSetType(pc,PCLU,self%ierr_ps)

call PCFactorSetMatSolverPackage(pc,MATSOLVERMUMPS,self%ierr_ps)

call PCFactorSetUpMatSolverPackage(pc,self%ierr_ps)

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

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