[petsc-users] BoomerAMG Hypre options

[Matthew Knepley]

On Sun, Apr 11, 2021 at 1:37 PM sthavishtha bhopalam <
sthavishthabr at gmail.com> wrote:

> Hello PETSc users
>
> I am trying to experiment with Hypre's BoomerAMG preconditioner which
> continually yields the error message "Linear solve did not converge due to
> DIVERGED_DTOL iterations 1". I would appreciate if someone can suggest some
> ways I could get BoomerAMG to yield converged results - the attached output
> shows a snippet of the error message. *Command Line options I used for
> BoomerAMG* : *-pc_type hypre -pc_hypre_type boomeramg
> -pchypreboomeramgtol 1.0e-3 -pchypreboomeramgstrongthreshold 0.25 -ksp_type
> richardson -pc_hypre_boomeramg_max_iter 6 -snes_rtol 1.0e-3 -ksp_rtol
> 1.0e-3 -ksp_view -snes_view -ksp_monitor -snes_monitor -ksp_max_it 100
> -ksp_converged_reason -snes_converged_reason*
>
> I also tried using *-ksp_type gmres*, different values of
> *-pc_hypre_boomeramg_max_iter*, *-pchypreboomeramgstrongthreshold*,
> *-ksp_initial_guess_nonzero* but all yielded the same error message.
>
> However, the direct solver converges as required - the attached output
> shows a snippet of the norms from the SNES and KSP.
> *Command Line options I used for the direct solver* : *-ksp_type gmres
> -pc_type lu -pc_factor_shift_type nonzero -pc_factor_mat_solver_type mumps
> -snes_converged_reason -ksp_converged_reason -ksp_rtol 1e-3 -snes_rtol 1e-3
> -ksp_monitor -snes_monitor*
>
> There is no particular reason for using the AMG here, but I just wanted to
> familiarize with it's options to see which of them need to be particularly
> tuned to yield converged and correct results.
>

Hypre is only going to work for a very specific set of systems. What are
you solving?

  Thanks,

     Matt


> Thanks
> -------------------------------------------
> Regards
>
> Sthavishtha
>
>
>
>
>

-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener

https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>
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