analyze preconditioned operator?

Matt Funk mafunk at
Thu Oct 9 15:38:00 CDT 2008

Hi Jed,

what you suggest seems like it might be even more efficient for sparse 
matrices (which i am using) then using the KSPComputeExplicitOperator() 

However, what kind of call do i make to apply the preconditioner to the 
matrix. I have not really ever written a MatShell but it seems like there 
should still be some PetscFunction that allows me to apply the 

Or am i misunderstanding you ... ?


ps: also, did you mean to write B=PA where A is my original preconditioner?

On Thursday 09 October 2008, Jed Brown wrote:
> On Thu, Oct 9, 2008 at 20:22, Matt Funk <mafunk at> wrote:
> > i am using PETSC and on top of it also SLEPC to do some matrix analysis.
> > In Slepc i simply pass it the Petsc matrix to analyze it.
> > However, is there anyway to analyze the preconditioned matrix at all?
> You can certainly write a MatShell which applies B = P^-1 A and hand
> this to SLEPc with no preconditioner.  This seems like a common thing
> so maybe SLEPc has an option to use the preconditioned operator.
> Jed

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