On Sun, Apr 11, 2021 at 1:37 PM sthavishtha bhopalam < [email protected]> 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/>