GMRES iteration options

General Discussion
1

Dear All,
I would like to control the maximal number of iteration steps/absolute tolerance for the GMRES algorithm, but I couldn’t find the correct options.
Thanks a lot for information,
Alexei

2

Are you using PETSc?

3

It seems that on this particular machine load “PETSc” fails so this is the builtin (?) fgmres implementation,
set(A, solver=GMRES)

4

Then, I do not know.

5

How to do it with PETSc?

6

-ksp_max_it XY -ksp_rtol alpha -ksp_atol beta. See also KSPSetTolerances — PETSc 3.21.1 documentation and KSPSetFromOptions — PETSc 3.21.1 documentation.

1 Like
7

Thanks! Is there a way to display/output the number of iterations GMRES actually needed to converge?

8

-ksp_converged_reason, it’s in the documentation I sent, so I suggest you read those links…