Hi Barry,

My command line is :

mpiexec -np 46 ./a.out -options_left -poisson_ksp_view -poisson_ksp_type gmres -poisson_pc_type hypre -poisson_pc_type_hypre boomeramg > log

My result is :

/*KSP Object:(poisson_) 46 MPI processes
  type: gmres
GMRES: restart=30, using Classical (unmodified) Gram-Schmidt Orthogonalization with no iterative refinement
    GMRES: 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:(poisson_) 46 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 0.25
    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     Gaussian-elimination
    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:
  Matrix Object:   46 MPI processes
....

...
*//**//*#PETSc Option Table entries:
-options_left
-poisson_ksp_type gmres
-poisson_pc_type hypre
-poisson_pc_type_hypre boomeramg
#End of PETSc Option Table entries
There is one unused database option. It is:
Option left: name:-poisson_pc_type_hypre value: boomeramg*/

It seems that it is using boomeramg but why does it say "one unused database option"?

Did I do something wrong?

Also if only my RHS of the Poisson eqn's changes, do I set the ksp and pc once at the start? E.g. :

call KSPSetType(ksp,ksptype,ierr)

ksptype=KSPGMRES

call PCSetType(pc,'hypre',ierr)

call PCHYPREGetType(pc,'boomeramg',ierr)

or do I have to do it at each time step?

Thank you

Yours sincerely,

TAY wee-beng

On 18/3/2014 2:23 AM, Barry Smith wrote:
  Yes. You can run with -poisson_ksp_view and -options_left to make sure the 
options you provide are actually used.

    Barry

On Mar 17, 2014, at 9:39 AM, TAY wee-beng <[email protected]> wrote:

Hi,

I use

call KSPSetOptionsPrefix(ksp_semi_xyz,"momentum_",ierr)

and

call KSPSetOptionsPrefix(ksp,"poisson_",ierr)

so that I can choose separate ksp/pc options for my momentum and poisson 
equations through command line e.g.

-poisson_ksp_type gmres -poisson_pc_type hypre -poisson_pc_type_hypre boomeramg

In general, I need to use boomeramg as the preconditioner and gmres as the 
solver for my poisson eqn, separate from my momentum eqn, which has its own 
default pc and ksp. Is the above the correct way?

Thanks!

--
Yours sincerely,

TAY wee-beng


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