[petsc-users] PCKSP

[Matthew Knepley]

On Tue, Jun 19, 2012 at 10:33 AM, Margarita Satraki <
margarita.satraki at gmail.com> wrote:

> Hello,
>
> I have difficulty understanding how PCKSP works.
>
> From:
>
> http://www.mcs.anl.gov/petsc/documentation/tutorials/Columbia04/DDandMultigrid.pdf
> I understand that instead of using preconditioners, it uses Krylov methods
> for the ''inner solvers''.
>
> What are the ''inner solvers''? Is there some kind of a subsystem that is
> solved instead of applying a preconditioner?
>

Nope, its jsut like a PC:

  M^{-1} A x = M^{-1} b

where now M^{-1} instead of being an LU solve, for instance, is a Krylov
solve.

   Matt


> Many thanks,
>
> Margarita
>



-- 
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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