[petsc-users] MatSetNearNullSpace and BoomerAMG ?

[Jed Brown]

Natacha BEREUX <natacha.bereux at gmail.com> writes:

> OK, thanks a lot Jed for your quick answer.
>
> I have a second question on multigrid :
> I define a matrix block size (equal to 3). Is this mandatory for any type
> of multigrid preconditioner (BoomerAMG, ML and GAMG) ?
> Or is it only  required with  ML and GAMG ?

It is always preferable.  BoomerAMG distinguishes those components in
its coarsening, it just doesn't use the near null space explicitly.
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