[petsc-users] GMRES pc right fails while pc left succeeds

[Klaij, Christiaan]

> > Both approximations are in the preconditioner.
>
>
> I'm afraid I don't have an explanation based on the information you have
> sent. If you can set up a test case that shows the issue, I'll investigate
> further.

Thanks for offering, unfortunately I don't have a small testcase that
shows the same behaviour. It only happens in the odd industrial case,
convergence is fine for most similar cases and perfect for small
academic cases.

>
> I would think about null space issues. For example, if the Schur complement
> has constants in its null space, but the right hand side is not consistent
> and/or the KSP was not informed of the null space.

Definitely not the constant, but there could be a near null space...


dr. ir. Christiaan Klaij
CFD Researcher
Research & Development
E mailto:C.Klaij at marin.nl
T +31 317 49 33 44

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