[petsc-users] Motivation for default KSP solver and PC

[Lawrence Mitchell]

> On 21 Sep 2020, at 14:03, Matthew Knepley <knepley at gmail.com> wrote:
> 
> On Mon, Sep 21, 2020 at 8:51 AM Luciano Siqueira <luciano.siqueira at usp.br> wrote:
> Hi *,
> 
> I'm experimenting with different combinations of KSP solvers and PCs and 
> I don't know why GMRES/bjacobi are the default choices for CPU and 
> 
> GMRES is chosen because it is monotonic in the 2-norm, and also faster than any other
> Krylov method in terms of iterates if you do not restart.

Counterpoint: https://doi.org/10.1137/0613049

Lawrence