[petsc-users] Problem with SNES

[Barry Smith]

On Aug 27, 2011, at 12:42 PM, Jed Brown wrote:

> On Sat, Aug 27, 2011 at 12:22, Milan Mitrovic <milan.v.mitrovic at gmail.com> wrote:
> [1]PETSC ERROR: Unknown Mat type given: same!
> 
> What kind of Mat were you assembling? Are you passing any other flags? What does your code assemble for the Jacobian? I think the Jacobian you passed in does not implement MatDuplicate(). I just changed MatConvert() to be more robust in petsc-dev.
> 
> With 3.1, you can try -pc_type lu -snes_monitor -ksp_monitor_singular_value. Also compare output with -snes_mf_operator. I think your Jacobian may be singular and this should help figure that out.

   See also http://www.mcs.anl.gov/petsc/petsc-as/documentation/faq.html#newton for various tips on dealing with a non-converging Newton.

    Barry