[petsc-dev] Algebraic Multigrid

[Mark Adams]

Oh, actually this worked.  You have this ...pc_type jacobi in there twice,
so one of them was "unused".

Try this with 2 processors now.

On Tue, Jul 26, 2016 at 6:42 PM, Mark Adams <mfadams at lbl.gov> wrote:

>
>
> On Tue, Jul 26, 2016 at 6:24 PM, Ari Rappaport <arir at vosssci.com> wrote:
>
>> So I commented out the line PCSetType(pc, PCGAMG). The line
>> KSPSetFromOptions(ksp) was already in the code at the end of our
>> initialization routine. I also added .petscrc to the working dir. Here is
>> the current output. It seems as if Option left: name:-mg_levels_pc_type
>> jacobi (no value) is still present in the output..I dunno.
>>
>
> Yea, I dunno either.  If you use -help you will get printout of the
> available options.  If you do this you will see stuff like -mg_levels_1_
> ... you can also see this in the ksp_view.  There is a shortcut that lets
> you _not_ put "_1" in.  Try putting this in for each level like so:
>
> -mg_levels_1_pc_type jacobi
> -mg_levels_2_pc_type jacobi
> -mg_levels_3_pc_type jacobi
>
> I also notice that the coarse grid ksp is GMRES.  This is our fault.  It
> should be preonly. Add:
>
> -mg_coarse_ksp_type preonly
>
>
>
>
>
>
>
>
>>
>> -Ari
>>
>> ----- Original Message -----
>> From: "Mark Adams" <mfadams at lbl.gov>
>> To: "Ari Rappaport" <arir at vosssci.com>, "For users of the development
>> version of PETSc" <petsc-dev at mcs.anl.gov>
>> Sent: Tuesday, July 26, 2016 4:03:03 PM
>> Subject: Re: [petsc-dev] Algebraic Multigrid
>>
>>
>> At the end of this you have:
>>
>>
>>
>> #PETSc Option Table entries:
>> -ksp_view
>> -mg_levels_pc_type jacobi
>> -options_left
>> #End of PETSc Option Table entries
>> There is one unused database option. It is:
>> Option left: name:-mg_levels_pc_type jacobi (no value)
>>
>>
>> So this jacobi parameter is not being used.
>>
>>
>> Do you call KPSSetFromOptions? Do you set solver parameters in the code?
>> Like PCGAMG?
>>
>>
>> You should not set anything in the code, it just confuses things at this
>> point. Use KSPSetFromOptions(). You can hardwire stuff before this call,
>> this just lets you set the defaults, but you should always call this last
>> to let command line parameters override the defaults.
>>
>>
>> You can put this in a .petscrc file in the working directory and try
>> again.
>>
>>
>>
>> -ksp_type cg
>> -ksp_max_it 50
>>
>> -ksp_rtol 1.e-6
>> -ksp_converged_reason
>> -pc_type gamg
>> -pc_gamg_type agg
>> -pc_gamg_agg_nsmooths 1
>> -pc_gamg_coarse_eq_limit 10
>> -pc_gamg_reuse_interpolation true
>> -pc_gamg_square_graph 1
>> -pc_gamg_threshold -0.05
>> -mg_levels_ksp_max_it 2
>> -mg_levels_ksp_type chebyshev
>> -mg_levels_esteig_ksp_type cg
>> -mg_levels_esteig_ksp_max_it 10
>> -mg_levels_ksp_chebyshev_esteig 0,.05,0,1.05
>> -mg_levels_pc_type jacobi
>> -pc_hypre_type boomeramg
>> -pc_hypre_boomeramg_no_CF
>> -pc_hypre_boomeramg_agg_nl 1
>> -pc_hypre_boomeramg_coarsen_type HMIS
>> -pc_hypre_boomeramg_interp_type ext+i
>>
>>
>
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