analyze preconditioned operator?

Matt Funk mafunk at
Thu Oct 9 15:33:59 CDT 2008

I think this is what i want (I hope i can run it though (in terms of memory)).
I had not noticed this function before. I'll give it a shot.


On Thursday 09 October 2008, you wrote:
> Take a look at KSPComputeExplicitOperator() routine. Note that it
> could be rather slow if your large matrices. Additionally, it returns
> a dense matrix in the uniprocessor case.
> It this trick does not fit your need, then perhaps you could use a
> shell matrix having the actual Mat and a PC, but that approach is a
> bit harder to setup.
> On Thu, Oct 9, 2008 at 3:22 PM, Matt Funk <mafunk at> wrote:
> > Hi,
> >
> > 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?
> >
> > The only ways i can think of are either by getting the preconditioned
> > matrix back out of PETSC (i.e. some sort of pointer to it if it is stored
> > at all), or by Slepc applying the preconditioner (i tried to contact the
> > developers but no one has responded to that question so far)?
> >
> > I looked around a little bit but i could not find anything on this.
> > Does anyone have experience with this?
> >
> > thanks
> > matt

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