[petsc-dev] Mark, what's the rational for keeping the Chebyshev tuning inside GAMG?

Jed Brown jed at jedbrown.org
Sun Feb 22 09:32:31 CST 2015

Barry Smith <bsmith at mcs.anl.gov> writes:
>    Huhh? 

The smoothed interpolation satisfies

  P_{smoothed} = (1 - w D^{-1} A) P_{tentative}

where D^{-1} is Jacobi (could be point-block Jacobi), but cannot be SOR.
GAMG is computing the estimate in order to choose w.

>    But anyways, even if GAMG turns on Cheby/Jacobi as the smoother
>    there is not reason the Chebyshev estimator you wrote cannot be
>    used since it just uses whatever PC has been set. So your response
>    seems completely orthogonal to my question. Can we merge and just
>    have one Chebyshev estimator?

I think yes, after adding KSPChebyshevGetEigenvalues().
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