[petsc-users] help needed for -snes_mf_operator

[Jed Brown]

On Wed, Apr 25, 2012 at 16:06, Dominik Szczerba <dominik at itis.ethz.ch>wrote:

> I am happy to be guilty if I know how I can improve: why do I get the
> right results without this option, for several cases?
>

How do you define "right results"? Is SNES converging quadratically when
you do not use -snes_mf_operator?


>
> > Run with -snes_type test and see what it reports.
>
> The moment I specify this option I get:
>
> [0]PETSC ERROR: Invalid argument!
> [0]PETSC ERROR: Cannot test with alternative preconditioner!
>
> tracing back to SNESSolve()
>

You either (a) set different matrices for the operator and preconditioning
matrix or (b) passed -snes_mf. Just pass one matrix.
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