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
