> On Aug 10, 2016, at 2:52 PM, Ari Rappaport <[email protected]> wrote:
>
> Hi Mark,
> There was indeed a bug on our end. Now that we fixed it everything is working
> correctly even in parallel. I have one question still though. Is there a way
> to get the mg_levels_pc_type jacobi option
> set in the code without passing it as an argument to PetscInitialize? I'm
> using PCGAMGSetType(pc, PCJACOBI) but it doesn't seem to be working.
You can call PetscOptionsSetValue("-<appropriate
prefix>_mg_levels_pc_type","jacobi") in the code anywhere before your code
creates the SNES or KSP object you are using. This is equivalent to putting it
on the command line.
Barry
>
>
> -Ari
>
> ----- Original Message -----
> From: "Mark Adams" <[email protected]>
> To: "Ari Rappaport" <[email protected]>
> Cc: "For users of the development version of PETSc" <[email protected]>
> Sent: Wednesday, July 27, 2016 7:24:24 PM
> Subject: Re: [petsc-dev] Algebraic Multigrid
>
> There is clearly something very wrong with your code. I would suggest
> starting with an example code for instance KSP/examples/tutorial/ex56.c and
> incrementally add your operator to get something that is working.
>
>
> Also if you have multiple degrees of freedom per vertex, for instance
> elasticity, then you want to set the block size of the matrix accordingly.
>
> On Wednesday, July 27, 2016, Ari Rappaport < [email protected] > wrote:
>
>
> Hi Mark,
> We added the Jacobi line and it appears to accept that flag now. However, we
> are getting all zeros for the solution vector. And PETSc is claiming to have
> converged in 7 iterations to the relative tolerance.
>
> -Ari
>
> ----- Original Message -----
> From: "Mark Adams" < [email protected] >
> To: "Ari Rappaport" < [email protected] >, "For users of the development
> version of PETSc" < [email protected] >
> Sent: Wednesday, July 27, 2016 3:26:03 PM
> Subject: Re: [petsc-dev] Algebraic Multigrid
>
>
> Please keep this on the Petsc list.
>
> We seem to have lost Jacobi smoother again. I'm suspecting that you're some
> funny character in your line with Jacobi that is Confusing the parser. Get
> back to the old file with the two two Jacobi entries and delete the other
> line and get Jacobi in the KSP view output. There should be no SOR in the
> output.
>
>
> On Wednesday, July 27, 2016, Ari Rappaport < [email protected] > wrote:
>
>
> Hi Mark,
> I added all these new things. The PCAMG is now ending very quickly but the
> residual is unreasonably large by about 10 orders of magnitude. I noticed the
> line "Linear solve did not converge due to DIVERGED_INDEFINITE_PC iterations
> 2" in the output, could this be causing the problem? It only appears to be
> going for 2 iterations now.
>
> -Ari
>
> ----- Original Message -----
> From: "Mark Adams" < [email protected] >
> To: "Ari Rappaport" < [email protected] >
> Cc: "For users of the development version of PETSc" < [email protected] >
> Sent: Tuesday, July 26, 2016 5:07:34 PM
> Subject: Re: [petsc-dev] Algebraic Multigrid
>
>
> Ari, I would also check that your operator is not messed up in parallel. The
> solver is looking pretty solid.
>
>
> Also, you can configure PETSc with hypre and use '-pc_type hypre'. If hypre
> is also good in serial but hosed on multi-proc then it is most probably your
> operator.
>
>
>
>
> On Tue, Jul 26, 2016 at 6:58 PM, Mark Adams < [email protected] > wrote:
>
>
>
> So remove one of the -mg_levels_pc_type jacobi and add -mg_coarse_ksp_type
> preonly, then verify that this works on one proc and then try two procs.
>
>
>
>
> On Tue, Jul 26, 2016 at 6:56 PM, Mark Adams < [email protected] > wrote:
>
>
>
> 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 < [email protected] > wrote:
>
>
>
>
>
>
>
> On Tue, Jul 26, 2016 at 6:24 PM, Ari Rappaport < [email protected] > 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" < [email protected] >
> To: "Ari Rappaport" < [email protected] >, "For users of the development
> version of PETSc" < [email protected] >
> 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
>
>
>
>
>
