[petsc-users] PETSc-gamg default setting

[藤井昭宏]

Hello everybody,

I’d like to compare a solver with PETSc-gamg for Poisson problems.
I used PETSc version 3.4.3., and the following command line option.

 -ksp_type “bcgs” -pc_type “gamg” -ksp_monitor -ksp_rtol 1.0E-7 -log_summary -pc_mg_log 


Would you give me some information on the following questions?

- Does this option correspond to BICGSTAB solver with smoothed aggregation algebraic multigrid method?

- Are coarser level small distributed matrices re-distributed to reduce the parallelism, when the number of processes is very large?

-  What kind of smoother will be used for this command line option?

-  pc_mg_log option shows the MG Apply stage. Does this stage time correspond to the solver time except for multi-level setup time?
   Does it include the time for BICGSTAB?


Thanks in advance.

Akihiro Fujii