[petsc-users] MatMult with factored matrix
Daniel L Crumly
daniel.crumly at Colorado.EDU
Thu Jul 8 12:18:05 CDT 2010
Thank you for the quick reply - I actually do want the action of the
factored matrix (or preconditioner) on a vector. Is there a recommended
workaround?
Thanks
Daniel "The Plaid Mentat" Crumly
Daniel.Crumly at colorado.edu
--------
I give you the desert chameleon, whose ability to blend itself into the
background tells you all you need to know about the roots of ecology and the
foundations of a personal identity.
--Book of Diatribes from the Hayt Chronicle
----Herbert, Frank. Children of Dune 28.
From: petsc-users-bounces at mcs.anl.gov
[mailto:petsc-users-bounces at mcs.anl.gov] On Behalf Of Matthew Knepley
Sent: Thursday, July 08, 2010 11:10 AM
To: PETSc users list
Subject: Re: [petsc-users] MatMult with factored matrix
On Thu, Jul 8, 2010 at 7:06 PM, Daniel L Crumly <daniel.crumly at colorado.edu>
wrote:
Hello all -
Is there a recommended way to multiply a factored matrix by a vector
(effectively MatMult where the matrix is a factored matrix or
preconditioner)? Specifically, I would like to get take the ILU
factorization of a matrix, then multiply a vector by this approximation.
Do you actually want the action, or the action of the inverse? We only
provide
the action of the inverse
http://www.mcs.anl.gov/petsc/petsc-as/snapshots/petsc-current/docs/manualpag
es/Mat/MatSolve.html
Matt
What I currently have is:
ierr = PCGetType(pc, &pctype);CHKERRQ(ierr);
if (strcmp(pctype, PCILU) == 0 || strcmp(pctype, PCICC) == 0) {
ierr = PCFactorGetMatrix(pc, &M);CHKERRQ(ierr);
ierr = MatMult(M, x, Mx);CHKERRQ(ierr);
}
which throws the runtime error (I'm currently using PETSc 3.0.0-p8.):
[0]PETSC ERROR: --------------------- Error Message
------------------------------------
[0]PETSC ERROR: Object is in wrong state!
[0]PETSC ERROR: Not for factored matrix!
[0]PETSC ERROR:
------------------------------------------------------------------------
Any suggestions are greatly appreciated, thank you.
Daniel "The Plaid Mentat" Crumly
Daniel.Crumly at colorado.edu
--------
I give you the desert chameleon, whose ability to blend itself into the
background tells you all you need to know about the roots of ecology and the
foundations of a personal identity.
--Book of Diatribes from the Hayt Chronicle
----Herbert, Frank. Children of Dune 28.
--
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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