[petsc-users] SNES solver

[Barry Smith]

On May 13, 2011, at 3:37 AM, Jed Brown wrote:

> On Fri, May 13, 2011 at 06:51, Tian(ICT) <rongtian at ncic.ac.cn> wrote:
> What does this output really mean?
> Why does a converged Newton iteration still lead to a diverged SNES solve?
> 
> 
> Newton did not converge.
>  
> 
> STEP 0 (Newton iterations: 3)
> 
> diverged reason: -6
> 
> You should consider using
> 
> PetscPrintf(comm,"%s\n",SNESConvergedReasons[reason]);
> 
> instead of printing the numeric value. Or just run with -snes_converged_reason to have PETSc print it for you before SNESSolve returns. The reason is SNES_DIVERGED_LINE_SEARCH

   See http://www.mcs.anl.gov/petsc/petsc-as/documentation/faq.html#newton for hints on why SNES is not converging.

   Barry