[Trilinos-Users] What are the best parameter choices for ML?

JR Cary cary at txcorp.com
Thu Sep 1 19:24:40 EDT 2016

We have trilinos as the solver in our code, and we present to users the
array of choices of parameters for ML:

    maximum levels = 30
    smoother type = ["Gauss Seidel" "symmetric variable block Gauss Seidel"
        "Jacobi" "Chebyshev" "Aztec"]
    smoother sweeps = 3
    when to smooth = ["before" "after" "both"]
    coarse type = ["Jacobi" "KLU"]
    damping factor = 1.333
    threshold = 0.0
    increase or decrease = ["increasing" "decreasing"]

so we get asked, "What should I choose?"

Are there any guidelines for this?  Or is it more a matter of trial and

For the present case we are doing Poisson with possibly highly varying

FYI, I did go to
Thought you might want to know that the first link for documentation is

I did look at mlguide.pdf, which I think is the suggestion, but it seems
to be more
of "how to select foo" rather than "why select foo".

Thanks for any help!

John Cary

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