[petsc-users] questions on hypre preconditioner

[Fande Kong]

Hi Developers,

There are two questions on the hypre preconditioner.

(1) How to set different relax types on different levels? It looks to use
the SAME relax type on all levels except the coarse level which we could
set it to a different solver. Especially, could I set the smoother type on
the finest level as NONE?

(2) How could I know how many levels have been actually created in hypre,
and how many unknowns on different levels?   The "-pc_view" can not tell me
this information:

 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:



Fande,
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