Hello,
I have been using PETSc for a couple of years with good success, but
lately as my linear problems have become stiffer (condition numbers of the
order of 1.e20), I am looking to use better preconditioners. I tried using PCMG
with all the default options (i.e., I just specified my preconditioner as PCMG
and did not add any options to it) and I am immediately seeing better
convergence.
What I am not sure of is why? I would like to know more about the
default parameters (the manual is not very explicit) and more importantly, want
to know why it is working even when I haven't specified any grid levels and
coarse grid operators. Any help in this regard will be appreciated.
Also, ultimately I want to use algebraic multigrid so is PCML a better
option than BoomerAMG? I tried BoomerAMG with mixed results.
Thanks,
Karthik
--
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Karthik Duraisamy
Assistant Professor (Consulting)
Durand Building Rm 357
Dept of Aeronautics and Astronautics
Stanford University
Stanford CA 94305
Phone: 650-721-2835
Web: www.stanford.edu/~dkarthik
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