Stopping criteria

[Matthew Knepley]

On Thu, Jan 15, 2009 at 10:24 AM, Nguyen, Hung V ERDC-ITL-MS <
Hung.V.Nguyen at usace.army.mil> wrote:

> Hello Matt,
>
> >however I would first check your matrix using -pc_type lu -ksp_type
> preonly
> to make sure its not singular.
>
> I got the error message below while running with option above. Do I have to
> build a matrix with type of seqaij/seqbaij to run with the -pc_type lu
> option?


1) Either run on a single process, or

2) Install a parallel LU, such as SuperLU --download-superlu

  Matt


>
> Thanks,
>
> -Hung
>
>
>
>  np ..       138524
>  np ..       143882
> [0]PETSC ERROR: --------------------- Error Message
> ------------------------------------
> [0]PETSC ERROR: [15]PETSC ERROR: [12]PETSC ERROR: [8]PETSC ERROR:
> --------------------- Error Message ------------------------------------
> [4]PETSC ERROR: [6]PETSC ERROR: --------------------- Error Message
> ------------------------------------
> [13]PETSC ERROR: --------------------- Error Message
> ------------------------------------
> --------------------- Error Message ------------------------------------
> [15]PETSC ERROR: [13]PETSC ERROR: No support for this operation for this
> object type!
> [12]PETSC ERROR: [15]PETSC ERROR: No support for this operation for this
> object type!
> No support for this operation for this object type!
> [12]PETSC ERROR: Matrix type mpiaij  symbolic LU!
> Matrix type mpiaij  symbolic LU!
> [13]PETSC ERROR: [15]PETSC ERROR: [12]PETSC ERROR: Matrix type mpiaij
> symbolic LU!
> [13]PETSC ERROR:
> ------------------------------------------------------------------------
>
>
>
> -----Original Message-----
> From: owner-petsc-users at mcs.anl.gov [mailto:owner-petsc-users at mcs.anl.gov]
> On
> Behalf Of Matthew Knepley
> Sent: Wednesday, January 14, 2009 2:05 PM
> To: petsc-users at mcs.anl.gov
> Subject: Re: Stopping criteria
>
> On Wed, Jan 14, 2009 at 1:54 PM, Nguyen, Hung V ERDC-ITL-MS
> <Hung.V.Nguyen at usace.army.mil> wrote:
>
>
>
>        Hello All,
>
>        I tried to solve an ill-conditioned system using cg with Jacobi
>        preconditioned. The KSP solver was stopping due to diverged reason
> within a
>        few iterations. Is there a way to keep KSP solver running until
> max_it?
>
>
> There is no way to continue CG here because it gets a zero divisor, and
> interprets this as an indefinite matrix. You can try GMRES, however I would
> first check your matrix using -pc_type lu -ksp_type preonly to make sure
> its
> not singular.
>
>  Matt
>
>
>
>        Thanks,
>
>        -hung
>
>        hvnguyen:jade23% aprun -n 16 ./test_matrix_read -ksp_type cg
> -pc_type
> jacobi
>        -ksp_rtol 1.0e-15 -ksp_max_it 50000 -ksp_monitor
> -ksp_converged_reason
>         0 KSP Residual norm 1.379074550666e+04
>         1 KSP Residual norm 7.252034661743e+03
>         2 KSP Residual norm 7.302184771313e+03
>         3 KSP Residual norm 1.162244351275e+04
>         4 KSP Residual norm 7.912531765659e+03
>         5 KSP Residual norm 4.094706251487e+03
>         6 KSP Residual norm 5.486131070301e+03
>         7 KSP Residual norm 6.367904529202e+03
>         8 KSP Residual norm 6.312767173219e+03
>        Linear solve did not converge due to DIVERGED_INDEFINITE_MAT
> iterations 9
>        Time in PETSc solver: 0.452695 seconds
>        The number of iteration       = 9
>        The solution residual error = 6.312767e+03
>
>
>
>
>
>
> --
> 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
>
>


-- 
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
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