[petsc-users] GMRES for outer solver

Jed Brown jed at jedbrown.org
Sat Apr 30 22:21:47 CDT 2022

In general, no. A fixed number of Krylov iterations (CG, GMRES, etc.) is a nonlinear operation.

A fixed number of iterations of a method with a fixed polynomial, such as Chebyshev, is a linear operation so you don't need a flexible outer method. 

Ramakrishnan Thirumalaisamy <rthirumalaisam1857 at sdsu.edu> writes:

> Hi,
> I have a Krylov solver with a preconditioner that is also a Krylov solver.
> I know I can use "fgmres" for the outer solver but can I use gmres for the
> outer solver with a fixed number of iterations in the Krylov
> preconditioners?
> Thanks,
> Rama

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