[petsc-users] having issues with nullspace

Mohammad Mirzadeh mirzadeh at gmail.com
Thu Mar 6 17:49:50 CST 2014


here's the output:

  0 KSP Residual norm 3.033840960250e+02

  1 KSP Residual norm 1.018974811826e+01

  2 KSP Residual norm 5.450493684941e-02

  3 KSP Residual norm 3.944064039516e-02

  4 KSP Residual norm 6.286181172600e-05

  5 KSP Residual norm 4.349133658643e-06

  6 KSP Residual norm 9.279429568232e-08

  7 KSP Residual norm 3.032522248740e-09

  8 KSP Residual norm 6.533747246875e-09

  9 KSP Residual norm 6.083185162500e-12

Linear solve converged due to CONVERGED_RTOL iterations 9

KSP Object: 1 MPI processes

  type: bcgs

  maximum iterations=10000, initial guess is zero

  tolerances:  relative=1e-12, absolute=1e-50, divergence=10000

  left preconditioning

  has attached null space

  using PRECONDITIONED norm type for convergence test

PC Object: 1 MPI processes

  type: hypre

    HYPRE BoomerAMG preconditioning

    HYPRE BoomerAMG: Cycle type V

    HYPRE BoomerAMG: Maximum number of levels 25

    HYPRE BoomerAMG: Maximum number of iterations PER hypre call 1

    HYPRE BoomerAMG: Convergence tolerance PER hypre call 0

    HYPRE BoomerAMG: Threshold for strong coupling 0.5

    HYPRE BoomerAMG: Interpolation truncation factor 0

    HYPRE BoomerAMG: Interpolation: max elements per row 0

    HYPRE BoomerAMG: Number of levels of aggressive coarsening 0

    HYPRE BoomerAMG: Number of paths for aggressive coarsening 1

    HYPRE BoomerAMG: Maximum row sums 0.9

    HYPRE BoomerAMG: Sweeps down         1

    HYPRE BoomerAMG: Sweeps up           1

    HYPRE BoomerAMG: Sweeps on coarse    1

    HYPRE BoomerAMG: Relax down          symmetric-SOR/Jacobi

    HYPRE BoomerAMG: Relax up            symmetric-SOR/Jacobi

    HYPRE BoomerAMG: Relax on coarse     symmetric-SOR/Jacobi

    HYPRE BoomerAMG: Relax weight  (all)      1

    HYPRE BoomerAMG: Outer relax weight (all) 1

    HYPRE BoomerAMG: Using CF-relaxation

    HYPRE BoomerAMG: Measure type        local

    HYPRE BoomerAMG: Coarsen type        Falgout

    HYPRE BoomerAMG: Interpolation type  classical

  linear system matrix = precond matrix:

  Mat Object:   1 MPI processes

    type: seqaij

    rows=263169, cols=263169

    total: nonzeros=1236141, allocated nonzeros=1244417

    total number of mallocs used during MatSetValues calls =0

      has attached null space

      not using I-node routines

On Thu, Mar 6, 2014 at 3:43 PM, Jed Brown <jed at jedbrown.org> wrote:

> Mohammad Mirzadeh <mirzadeh at gmail.com> writes:
> > Yes. To be precise this is the set of functions I call:
> >
> > ierr = MatNullSpaceCreate(mpicomm, PETSC_FALSE, 1, &null_space,
> > &A_null_space); CHKERRXX(ierr);
> >
> > ierr = MatSetNullSpace(A, A_null_space); CHKERRXX(ierr);
> >
> > ierr = KSPSetNullSpace(ksp, A_null_space); CHKERRXX(ierr);
> >
> > ierr = MatNullSpaceRemove(A_null_space, rhs_, NULL); CHKERRXX(ierr);
> Is the matrix symmetric?  If not, the right and left null spaces could
> be different, in which case this system might be inconsistent.
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