[petsc-users] Help with ML/BoomerAMG

Matthew Knepley knepley at gmail.com
Mon Apr 29 21:12:29 CDT 2013

On Mon, Apr 29, 2013 at 9:07 PM, Gaetan Kenway <gaetank at gmail.com> wrote:

> That makes sense. Is there a reasonably easy way of doing that in PETSc
> currently for reasonably large systems?

Jed is working on it :)


> Gaetan
> On Mon, Apr 29, 2013 at 4:32 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote:
>> Gaetan Kenway <gaetank at gmail.com> writes:
>> > I would be very interested in looking at the problematic eigenmodes as
>> > well. On my end I use Tecplot for all my visualization.  What sort of
>> > visualization technique are you thinking about? Is it the KSP subspace
>> > vectors you want to look at?
>> No, it would be an eigensolve for either outliers or eigenvalues very
>> close to zero.  The cost to find the vector is like several solves, but
>> it would tell us exactly what sort of functions are poorly approximated
>> by the preconditioner.  Then we would think about how we can change
>> algorithms to make the preconditioner correct those functions better.

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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