[petsc-dev] Algebraic Multigrid

Mark Adams mfadams at lbl.gov
Tue Jul 26 17:03:03 CDT 2016

At the end of this you have:

#PETSc Option Table entries:
-mg_levels_pc_type jacobi
#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?

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
-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_agg_nl 1
-pc_hypre_boomeramg_coarsen_type HMIS
-pc_hypre_boomeramg_interp_type ext+i
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