[petsc-users] Hypre BoomerAMG settings options database

[Mark Adams]

Does this work for you?

-pc_hypre_boomeramg_grid_sweeps_all 2

The comment in our code says SSOR is the default but it looks like it
is really "hSGS"

I thought it was an L1 Jacobi, but you would want to ask Hypre about this.

Mark



On Fri, Jan 5, 2024 at 10:21 AM Barry Smith <bsmith at petsc.dev> wrote:

>
>   Yes, the handling of BoomerAMG options starts at line 365. If we don't
> support what you want but hypre has a function call that allows one to set
> the values then the option could easily be added to the PETSc options
> database here either by you (with a merge request) or us. So I would say
> check the hypre docs.
>
>   Just let us know what BoomerAMG function is missing from the code.
>
>   Barry
>
>
> On Jan 5, 2024, at 7:52 AM, Khurana, Parv <p.khurana22 at imperial.ac.uk>
> wrote:
>
> Hello PETSc users community,
>
> Happy new year! Thank you for the community support as always.
>
> I am using BoomerAMG for my research, and it is interfaced to my software
> via PETSc. I can only use options database keys as of now to tweak the
> settings I want for the AMG solve.
>
> I want to control the number of smoothener iterations at pre/post step for
> a given AMG cycle. I am looking for an options database key which helps me
> control this. I am not sure whether this is possible directly via the keys
> (Line 365:
> https://www.mcs.anl.gov/petsc/petsc-3.5.4/src/ksp/pc/impls/hypre/hypre.c.html).
> My comprehension of the current setup is that I have 1 smoothener iteration
> at every coarsening step. My aim is to do two pre and 2 post smoothening
> steps using the SSOR smoothener.
>
> BoomerAMG SOLVER PARAMETERS:
>
>   Maximum number of cycles:         1
>   Stopping Tolerance:               0.000000e+00
>   Cycle type (1 = V, 2 = W, etc.):  1
>
>   Relaxation Parameters:
>    Visiting Grid:                     down   up  coarse
>             Number of sweeps:            1    1     1
>    Type 0=Jac, 3=hGS, 6=hSGS, 9=GE:      6    6     9
>    Point types, partial sweeps (1=C, -1=F):
>                   Pre-CG relaxation (down):   1  -1
>                    Post-CG relaxation (up):  -1   1
>                              Coarsest grid:   0
>
> PETSC settings I am using currently:
>
> -ksp_type preonly
> -pc_type hypre
> -pc_hypre_type boomeramg
> -pc_hypre_boomeramg_coarsen_type hmis
> -pc_hypre_boomeramg_relax_type_all symmetric-sor/jacobi
> -pc_hypre_boomeramg_strong_threshold 0.7
> -pc_hypre_boomeramg_interp_type ext+i
> -pc_hypre_boomeramg_P_max 2
> -pc_hypre_boomeramg_truncfactor 0.3
>
> Thanks and Best
> Parv Khurana
>
>
>
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