[petsc-users] Hypre BoomerAMG settings options database

[Pierre Jolivet]

> On 6 Jan 2024, at 3:15 PM, Mark Adams <mfadams at lbl.gov> wrote:
> 
> 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.
HYPRE’s default settings are not the same as the ones we set in PETSc as default, so do not ask HYPRE people (about this particular issue).

Thanks,
Pierre
> Mark
> 
> 
> On Fri, Jan 5, 2024 at 10:21 AM Barry Smith <bsmith at petsc.dev <mailto: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 <mailto: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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