> On Oct 4, 2018, at 6:09 PM, HeeHo Park <heeho.p...@gmail.com> wrote:
>
> Barry and Jed,
>
> Thank you for your answers. I think I need to learn more about domain
> decomposition as I am a bit confused.
> Is it true that we are using BiCGstab here to solve the system of equations,
> using Additive Schwartz as a domain decomposition preconditioner, and that
> precondition matrix for each block is preconditioned by ilu[0]?
You can say it that way.
>
> Thanks,
>
>
> On Thu, Oct 4, 2018 at 5:53 PM Smith, Barry F. <bsm...@mcs.anl.gov> wrote:
>
> Since
>
> KSP Object: (flow_sub_) 1 MPI processes
> type: preonly
>
> this means only a single iteration of the inner solver is used so the
> numbers in red are not used.
>
> You could do something like -flow_ksp_type fgmres -flow_sub_ksp_type gmres
> -flow_sub_ksp_rtol 1.e-2 but it wouldn't help maters. Likely the current
> values are the best.
>
> Barry
>
>
> > On Oct 4, 2018, at 5:44 PM, HeeHo Park <heeho.p...@gmail.com> wrote:
> >
> > Hi, I'm running PFLOTRAN and in PFLOTRAN, we have flow_ and flow_sub_
> > processes. I was wondering what the red underlined values meant (each block
> > tolerance?) and how to change them (would it affect convergence?). Blue
> > marked bold values are changed from the default values for linear solvers.
> >
> > FLOW Linear Solver
> > solver: bcgs
> > preconditioner: asm
> > atol: 1.000000E-10
> > rtol: 1.000000E-10
> > dtol: 1.000000E+04
> > maximum iteration: 10000
> > KSP Object: (flow_) 8 MPI processes
> > type: bcgs
> > maximum iterations=10000, initial guess is zero
> > tolerances: relative=1e-10, absolute=1e-10, divergence=10000.
> > left preconditioning
> > using PRECONDITIONED norm type for convergence test
> > PC Object: (flow_) 8 MPI processes
> > type: asm
> > Additive Schwarz: total subdomain blocks = 8, amount of overlap = 1
> > Additive Schwarz: restriction/interpolation type - RESTRICT
> > [0] number of local blocks = 1
> > [1] number of local blocks = 1
> > [2] number of local blocks = 1
> > [3] number of local blocks = 1
> > [4] number of local blocks = 1
> > [5] number of local blocks = 1
> > [6] number of local blocks = 1
> > [7] number of local blocks = 1
> > Local solve info for each block is in the following KSP and PC objects:
> > - - - - - - - - - - - - - - - - - -
> > [0] local block number 0, size = 1389
> > KSP Object: (flow_sub_) 1 MPI processes
> > type: preonly
> > maximum iterations=10000, initial guess is zero
> > >>> tolerances: relative=1e-05, absolute=1e-50, divergence=10000.
> > left preconditioning
> > using DEFAULT norm type for convergence test
> > PC Object: (flow_sub_) 1 MPI processes
> > type: ilu
> > PC has not been set up so information may be incomplete
> > out-of-place factorization
> > 0 levels of fill
> > tolerance for zero pivot 2.22045e-14
> > using diagonal shift on blocks to prevent zero pivot [INBLOCKS]
> > matrix ordering: natural
> > linear system matrix = precond matrix:
> > Mat Object: (flow_) 1 MPI processes
> > type: seqbaij
> > rows=1389, cols=1389, bs=3
> > total: nonzeros=20025, allocated nonzeros=20025
> > total number of mallocs used during MatSetValues calls =0
> > block size is 3
> > - - - - - - - - - - - - - - - - - -
> >
> > --
> > HeeHo Daniel Park
>
>
>
> --
> HeeHo Daniel Park