[petsc-dev] Multigrid is confusing

[Jed Brown]

On Wed, May 23, 2012 at 2:26 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:

>
>  This looks good:
>
> $ $base -mg_levels_ksp_type chebyshev
> -mg_levels_ksp_chebyshev_estimate_eigenvalues 0.1,1.1 -mg_levels_ksp_max_it
> 2 -mg_levels_pc_type sor
> lid velocity = 100, prandtl # = 1, grashof # = 10000
>  Linear solve converged due to CONVERGED_RTOL iterations 10
>  Linear solve converged due to CONVERGED_RTOL iterations 7
>  Linear solve converged due to CONVERGED_RTOL iterations 8
>  Linear solve converged due to CONVERGED_RTOL iterations 8
>  Linear solve converged due to CONVERGED_RTOL iterations 9
>  Linear solve converged due to CONVERGED_RTOL iterations 9
>  Linear solve converged due to CONVERGED_RTOL iterations 8
>  Linear solve converged due to CONVERGED_RTOL iterations 8
>  Linear solve converged due to CONVERGED_RTOL iterations 7
> Number of SNES iterations = 9
>
>    I assume it is independent of the number of levels of refinement?
>

$ $base -da_refine 0 -snes_grid_sequence 5 -mg_levels_ksp_type chebyshev
-mg_levels_ksp_chebyshev_estimate_eigenvalues 0.1,1.1 -mg_levels_ksp_max_it
2 -mg_levels_pc_type sor
lid velocity = 100, prandtl # = 1, grashof # = 10000
            Linear solve converged due to CONVERGED_RTOL iterations 13
            Linear solve converged due to CONVERGED_RTOL iterations 7
            Linear solve converged due to CONVERGED_RTOL iterations 8
            Linear solve converged due to CONVERGED_RTOL iterations 9
            Linear solve converged due to CONVERGED_RTOL iterations 7
            Linear solve converged due to CONVERGED_RTOL iterations 8
            Linear solve converged due to CONVERGED_RTOL iterations 10
            Linear solve converged due to CONVERGED_RTOL iterations 7
            Linear solve converged due to CONVERGED_RTOL iterations 12
            Linear solve converged due to CONVERGED_RTOL iterations 8
            Linear solve converged due to CONVERGED_RTOL iterations 11
          Linear solve converged due to CONVERGED_RTOL iterations 11
          Linear solve converged due to CONVERGED_RTOL iterations 11
          Linear solve converged due to CONVERGED_RTOL iterations 11
          Linear solve converged due to CONVERGED_RTOL iterations 11
          Linear solve converged due to CONVERGED_RTOL iterations 11
        Linear solve converged due to CONVERGED_RTOL iterations 14
        Linear solve converged due to CONVERGED_RTOL iterations 11
        Linear solve converged due to CONVERGED_RTOL iterations 11
        Linear solve converged due to CONVERGED_RTOL iterations 10
      Linear solve converged due to CONVERGED_RTOL iterations 9
      Linear solve converged due to CONVERGED_RTOL iterations 8
      Linear solve converged due to CONVERGED_RTOL iterations 8
      Linear solve converged due to CONVERGED_RTOL iterations 7
      Linear solve converged due to CONVERGED_RTOL iterations 8
    Linear solve converged due to CONVERGED_RTOL iterations 8
    Linear solve converged due to CONVERGED_RTOL iterations 6
    Linear solve converged due to CONVERGED_RTOL iterations 7
    Linear solve converged due to CONVERGED_RTOL iterations 6
  Linear solve converged due to CONVERGED_RTOL iterations 11
  Linear solve converged due to CONVERGED_RTOL iterations 7
  Linear solve converged due to CONVERGED_RTOL iterations 5
  Linear solve converged due to CONVERGED_RTOL iterations 5
Number of SNES iterations = 4


>
>  Note that you could use -pc_type eisenstat perhaps in this case instead.
> Might save lots of flops?  I've often wondered about doing Mark's favorite
> chebyshev smoother with Eisenstat, seems like it should be a good match.
>

[0]PETSC ERROR: --------------------- Error Message
------------------------------------
[0]PETSC ERROR: No support for this operation for this object type!
[0]PETSC ERROR: Cannot have different mat and pmat!



>
>
>
>   Barry
>
>
> On May 23, 2012, at 11:48 AM, Jed Brown wrote:
>
> > If ex19 is what matters...
> >
> > $ base='mpiexec.hydra -n 4 ./ex19 -da_refine 3 -lidvelocity 100 -grashof
> 1e4 -pc_type mg -ksp_type fgmres -pc_mg_type full -ksp_converged_reason'
> > $ $base
> > lid velocity = 100, prandtl # = 1, grashof # = 10000
> >   Linear solve converged due to CONVERGED_RTOL iterations 23
> >   Linear solve converged due to CONVERGED_RTOL iterations 12
> >   Linear solve converged due to CONVERGED_RTOL iterations 12
> >   Linear solve converged due to CONVERGED_RTOL iterations 17
> >   Linear solve converged due to CONVERGED_RTOL iterations 15
> >   Linear solve converged due to CONVERGED_RTOL iterations 13
> >   Linear solve converged due to CONVERGED_RTOL iterations 19
> >   Linear solve converged due to CONVERGED_RTOL iterations 21
> >   Linear solve converged due to CONVERGED_RTOL iterations 18
> > Number of SNES iterations = 9
> > $ $base -mg_levels_ksp_type chebyshev
> -mg_levels_ksp_chebyshev_estimate_eigenvalues 0.1,1.1 -mg_levels_ksp_max_it
> 1 -mg_levels_pc_type pbjacobi
> > lid velocity = 100, prandtl # = 1, grashof # = 10000
> >   Linear solve converged due to CONVERGED_RTOL iterations 25
> >   Linear solve converged due to CONVERGED_RTOL iterations 27
> >   Linear solve converged due to CONVERGED_RTOL iterations 27
> >   Linear solve converged due to CONVERGED_RTOL iterations 30
> >   Linear solve converged due to CONVERGED_RTOL iterations 28
> >   Linear solve converged due to CONVERGED_RTOL iterations 42
> >   Linear solve converged due to CONVERGED_RTOL iterations 49
> >   Linear solve converged due to CONVERGED_RTOL iterations 52
> >   Linear solve converged due to CONVERGED_RTOL iterations 48
> > Number of SNES iterations = 9
> > $ $base -mg_levels_ksp_type chebyshev
> -mg_levels_ksp_chebyshev_estimate_eigenvalues 0.1,1.1 -mg_levels_ksp_max_it
> 1 -mg_levels_pc_type sor
> > lid velocity = 100, prandtl # = 1, grashof # = 10000
> >   Linear solve converged due to CONVERGED_RTOL iterations 22
> >   Linear solve converged due to CONVERGED_RTOL iterations 16
> >   Linear solve converged due to CONVERGED_RTOL iterations 17
> >   Linear solve converged due to CONVERGED_RTOL iterations 19
> >   Linear solve converged due to CONVERGED_RTOL iterations 19
> >   Linear solve converged due to CONVERGED_RTOL iterations 17
> >   Linear solve converged due to CONVERGED_RTOL iterations 20
> >   Linear solve converged due to CONVERGED_RTOL iterations 18
> >   Linear solve converged due to CONVERGED_RTOL iterations 17
> > Number of SNES iterations = 9
> > $ $base -mg_levels_ksp_type chebyshev
> -mg_levels_ksp_chebyshev_estimate_eigenvalues 0.1,1.1 -mg_levels_ksp_max_it
> 2 -mg_levels_pc_type pbjacobi
> > lid velocity = 100, prandtl # = 1, grashof # = 10000
> >   Linear solve converged due to CONVERGED_RTOL iterations 15
> >   Linear solve converged due to CONVERGED_RTOL iterations 13
> >   Linear solve converged due to CONVERGED_RTOL iterations 16
> >   Linear solve converged due to CONVERGED_RTOL iterations 15
> >   Linear solve converged due to CONVERGED_RTOL iterations 16
> >   Linear solve converged due to CONVERGED_RTOL iterations 16
> >   Linear solve converged due to CONVERGED_RTOL iterations 18
> >   Linear solve converged due to CONVERGED_RTOL iterations 17
> >   Linear solve converged due to CONVERGED_RTOL iterations 16
> > Number of SNES iterations = 9
> > $ $base -mg_levels_ksp_type chebyshev
> -mg_levels_ksp_chebyshev_estimate_eigenvalues 0.1,1.1 -mg_levels_ksp_max_it
> 2 -mg_levels_pc_type sor
> > lid velocity = 100, prandtl # = 1, grashof # = 10000
> >   Linear solve converged due to CONVERGED_RTOL iterations 10
> >   Linear solve converged due to CONVERGED_RTOL iterations 7
> >   Linear solve converged due to CONVERGED_RTOL iterations 8
> >   Linear solve converged due to CONVERGED_RTOL iterations 8
> >   Linear solve converged due to CONVERGED_RTOL iterations 9
> >   Linear solve converged due to CONVERGED_RTOL iterations 9
> >   Linear solve converged due to CONVERGED_RTOL iterations 8
> >   Linear solve converged due to CONVERGED_RTOL iterations 8
> >   Linear solve converged due to CONVERGED_RTOL iterations 7
> > Number of SNES iterations = 9
> > $ $base -mg_levels_ksp_type chebyshev
> -mg_levels_ksp_chebyshev_estimate_eigenvalues 0.1,1.1 -mg_levels_ksp_max_it
> 3 -mg_levels_pc_type pbjacobi
> > lid velocity = 100, prandtl # = 1, grashof # = 10000
> >   Linear solve converged due to CONVERGED_RTOL iterations 12
> >   Linear solve converged due to CONVERGED_RTOL iterations 9
> >   Linear solve converged due to CONVERGED_RTOL iterations 11
> >   Linear solve converged due to CONVERGED_RTOL iterations 11
> >   Linear solve converged due to CONVERGED_RTOL iterations 11
> >   Linear solve converged due to CONVERGED_RTOL iterations 12
> >   Linear solve converged due to CONVERGED_RTOL iterations 12
> >   Linear solve converged due to CONVERGED_RTOL iterations 11
> >   Linear solve converged due to CONVERGED_RTOL iterations 11
> > Number of SNES iterations = 9
> > $ $base -mg_levels_ksp_type chebyshev
> -mg_levels_ksp_chebyshev_estimate_eigenvalues 0.1,1.1 -mg_levels_ksp_max_it
> 3 -mg_levels_pc_type sor
> > lid velocity = 100, prandtl # = 1, grashof # = 10000
> >   Linear solve converged due to CONVERGED_RTOL iterations 9
> >   Linear solve converged due to CONVERGED_RTOL iterations 6
> >   Linear solve converged due to CONVERGED_RTOL iterations 6
> >   Linear solve converged due to CONVERGED_RTOL iterations 7
> >   Linear solve converged due to CONVERGED_RTOL iterations 7
> >   Linear solve converged due to CONVERGED_RTOL iterations 6
> >   Linear solve converged due to CONVERGED_RTOL iterations 7
> >   Linear solve converged due to CONVERGED_RTOL iterations 6
> >   Linear solve converged due to CONVERGED_RTOL iterations 6
> > Number of SNES iterations = 9
> >
>
>
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