[petsc-users] L infinity norm convergence tests

[Jed Brown]

Matthew Knepley <knepley at gmail.com> writes:

> On Wed, Jun 10, 2020 at 9:02 AM Mark Lohry <mlohry at gmail.com> wrote:
>
>> Hi all, is there a built-in way to use L-infinity norms for the SNES and
>> KSP convergence tests, or do I need to write a manual KSPSetConvergenceTest
>> function?
>>
>
> You need to write a custom test.

Note that it may incur a large cost with some methods.  In GMRES, for
example, the solution and residual are not explicitly available on each
iteration.  They are in GCR, at the cost of storing two vectors per
Krylov iteration instead of one for GMRES.