[petsc-users] help needed for -snes_mf_operator

[Dominik Szczerba]

> My guess is that your "exact" Jacobian  is wrong

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?

> 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()

Dominik