[Trilinos-Users] Jacobi and Gauss-Seidel smoothers

[Hoemmen, Mark]

On 9/19/16, 10:19 AM, "Trilinos-Users on behalf of trilinos-users-request at trilinos.org" <trilinos-users-bounces at trilinos.org on behalf of trilinos-users-request at trilinos.org> wrote:
>Date: Tue, 13 Sep 2016 18:35:23 +0100
>From: Martin Vymazal <martin.vymazal at vki.ac.be>
>To: trilinos-users at trilinos.org
>Subject: Re: [Trilinos-Users] Jacobi and Gauss-Seidel smoothers
>Message-ID: <cf20279e3d0cba25b08ea6be72469c15 at vki.ac.be>
>Content-Type: text/plain; charset=US-ASCII; format=flowed
>
> . . . doesn't the example use the object 'M' as preconditioner? I'm sorry 
>but I don't see any calls to apply(). What's the difference between the 
>usage of M as preconditioner and smoother?

Ifpack2 does not distinguish between preconditioners and smoothers.  Ifpack2::Relaxation implements Jacobi, Gauss-Seidel, and (S)SOR.  It’s up to the user whether to use these algorithms as preconditioners or smoothers.  Ifpack2 classes implement Tpetra::Operator, so you can just call apply().

mfh