[petsc-dev] Scalability of removing null spaces

[Matthew Knepley]

On Sun, Jul 22, 2012 at 1:19 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote:

> We recommend to people that they just call MatSetNullSpace() and solve the
> singular system. What if reductions are very expensive? Are there Krylov
> methods that accommodate a pipelined or deferred null space removal?
> Shouldn't be hard to do, but I haven't seen papers on it.


I think we have to figure out how to do this pipelined thing in a
mechanical way (not necessarily automated, but
done without thinking). You would think this had been figured out by the
architecture guys.

   Matt

-- 
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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