> 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
