[petsc-users] (no subject)

[Matthew Knepley]

On Fri, Dec 7, 2018 at 10:05 AM Yingjie Wu via petsc-users <
petsc-users at mcs.anl.gov> wrote:

> Dear Petsc developer:
> Hi,
> I recently begin a new program, which is a two-dimensional nonlinear PDEs
> problem, and solved by SNES.  However, there is an error. The log is :
>
> Linear solve did not converge due to DIVERGED_PCSETUP_FAILED iterations 0
>                  PCSETUP_FAILED due to FACTOR_NUMERIC_ZEROPIVOT
> Nonlinear solve did not converge due to DIVERGED_LINEAR_SOLVE iterations 0
> SNES Object: 1 MPI processes
>   type: newtonls
>   maximum iterations=50, maximum function evaluations=10000
>   tolerances: relative=1e-08, absolute=1e-50, solution=1e-08
>   total number of linear solver iterations=0
>   total number of function evaluations=18903
>   norm schedule ALWAYS
>   Jacobian is built using finite differences one column at a time
>   SNESLineSearch Object: 1 MPI processes
>     type: bt
>       interpolation: cubic
>       alpha=1.000000e-04
>     maxstep=1.000000e+08, minlambda=1.000000e-12
>     tolerances: relative=1.000000e-08, absolute=1.000000e-15,
> lambda=1.000000e-08
>     maximum iterations=40
>   KSP Object: 1 MPI processes
>     type: gmres
>       restart=30, using Classical (unmodified) Gram-Schmidt
> Orthogonalization with no iterative refinement
>       happy breakdown tolerance 1e-30
>     maximum iterations=10000, initial guess is zero
>     tolerances:  relative=1e-05, absolute=1e-50, divergence=10000.
>     left preconditioning
>     using PRECONDITIONED norm type for convergence test
>   PC Object: 1 MPI processes
>     type: lu
>       out-of-place factorization
>       tolerance for zero pivot 2.22045e-14
>       matrix ordering: nd
>       factor fill ratio given 5., needed 20.7926
>         Factored matrix follows:
>           Mat Object: 1 MPI processes
>             type: seqaij
>             rows=18901, cols=18901
>             package used to perform factorization: petsc
>             total: nonzeros=3029644, allocated nonzeros=3029644
>             total number of mallocs used during MatSetValues calls =0
>               not using I-node routines
>     linear system matrix = precond matrix:
>     Mat Object: 1 MPI processes
>       type: seqaij
>       rows=18901, cols=18901
>       total: nonzeros=145708, allocated nonzeros=341390
>       total number of mallocs used during MatSetValues calls =16459
>         not using I-node routines
>
> I used "-snes_fd -pc_type lu" to test the program.
> The error shows that there are some zero elements in the matrix. What
> might cause this problem?
>

Error in the residual? It looks like changes in some variable do not effect
it.

  Thanks,

     Matt


> Thanks,
> Yingjie
>


-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener

https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>
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