My settings are overriden when I call the solver more than once?

[Sh.M]

Hi,

Thanks for the thorough explanation!

With best regards, Shaman Mahmoudi

On Tue, 18 Apr 2006, Barry Smith wrote:

>
>     What controls the iteration max and tolerance for Richardson
> solver is -inner_ksp_max_its <its> and -inner_ksp_rtol <rtol>
> This is true for any preconditioner including hypre boomeramg.
> The defaults are 10000 and 1.e-5.
>
> The problem is that the options
> -inner_pc_hypre_boomeramg_max_iter 4
> -inner_pc_hypre_boomeramg_tol 1.0e-06
> sure look like THEY should control this. Hence the confusion.
>
> Here is the issue, pc_hypre_boomeramg_max_iter and pc_hypre_boomeramg_tol are
> suppose to control (with PETSc) how many iterations boomeramg does WITHIN a
> single call to ITS solve. Say we used a ksp of gmres and a pc_hypre_boomeramg_max_iter 4
> this means we are using preconditioned gmres with a preconditioner of FOUR V cycles
> of boomeramg (this is different then using preconditioned gmres with a preconditioner of
> ONE cycle). Completely possible and maybe a reasonable thing to do.
>
> The error in PETSc is that paragraph three above does NOT hold for Richardsons method
> (but it does hold for all other KSP methods). This is because Richardson's method
> has a "special method" PCApplyRichardson() that avoids the overhead of explicitly
> applying Richardson's method (see src/ksp/ksp/impls/rich/rich.c). I did not handle
> this properly when I wrote the PCApplyRichardson_BoomerAMG. I will fix this error.
>
> Anyways, the short answer is when using Richardson with hypre
> use -inner_ksp_max_its <its> and -inner_ksp_rtol <rtol> to control
> the iterations and tolerance, NOT
> -inner_pc_hypre_boomeramg_max_iter
> and -inner_pc_hypre_boomeramg_tol
> I will attempt to make the docs clearer.
>
>
>     Barry
>
>
>
>
>
> On Tue, 18 Apr 2006, Sh.M wrote:
>
> > Hi all,
> >
> > I am solving a matrix with boomerAMG, and I set the boomerAMG settings
> > thru the console. The matrix(it is a preconditioner matrix) is solved
> > several times... I set the boomerAMG preconditioner/solver to have a
> > convergence tolerance of 1.0e-06 and max number of iterations 4. I print out boomerAMG status to
> > verify that it works as it should.. But for some reason it doesnt..
> >
> > Here is a print from boomerAMG when it starts, I guess when it constructs
> > the boomerAMG solver/preconditioner:
> >
> > .
> > .
> > .
> > .
> > .
> > .
> > BoomerAMG SOLVER PARAMETERS:
> >
> >  Maximum number of cycles:         4
> >  Stopping Tolerance:               1.000000e-06
> >  Cycle type (1 = V, 2 = W, etc.):  1
> >
> >  Relaxation Parameters:
> >   Visiting Grid:                     fine  down   up  coarse
> >            Number of partial sweeps:   1     1    1     1
> >   Type 0=Jac, 1=GS, 3=Hybrid 9=GE:     3     3    3     9
> >   Point types, partial sweeps (1=C, -1=F):
> >                               Finest grid:   1  -1
> >                  Pre-CG relaxation (down):   1  -1
> >                   Post-CG relaxation (up):  -1   1
> >                             Coarsest grid:   0
> >
> >
> >
> > Immediately after the above message, wich is when it starts to
> > solve, it changes its parameters to this:
> >
> >
> > BoomerAMG SOLVER PARAMETERS:
> >
> >  Maximum number of cycles:         10000
> >  Stopping Tolerance:               1.000000e-05
> >  Cycle type (1 = V, 2 = W, etc.):  1
> >
> >  Relaxation Parameters:
> >   Visiting Grid:                     fine  down   up  coarse
> >            Number of partial sweeps:   1     1    1     1
> >   Type 0=Jac, 1=GS, 3=Hybrid 9=GE:     3     3    3     9
> >   Point types, partial sweeps (1=C, -1=F):
> >                               Finest grid:   1  -1
> >                  Pre-CG relaxation (down):   1  -1
> >                   Post-CG relaxation (up):  -1   1
> >                             Coarsest grid:   0
> > .
> > .
> > .
> > .
> > .
> > .
> >
> >
> > As you see my settings have been changed.
> >
> > I have used boomerAMG in the past, not exactly this way.,... but my
> > settings were preserved before and after solve.
> >
> > here is what I run from the command line:
> >
> > mprun -np 1 petscSolver
> > -a ../hypre/data/nr_hvl40.csr
> > -b ../hypre/data/nr_hvl40.csr.blockMatrix -inner_ksp_type richardson
> > -inner_pc_type hypre -inner_pc_hypre_type boomeramg
> > -inner_pc_hypre_boomeramg_max_iter 4
> > -inner_pc_hypre_boomeramg_tol 1.0e-06
> > -ksp_monitor
> > -ksp_type gmres
> > -inner_pc_hypre_boomeramg_print_statistics
> >
> >
> > And a piece of code:
> >
> > .
> > .
> > .
> > .
> > .
> > .
> > BLOCK_PC  user_pc;
> > ,
> > ,
> > ,
> > ,
> > ,
> > .
> > KSPSetOptionsPrefix(user_pc.block_solver,"inner_");
> > KSPSetOperators(user_pc.block_solver,user_pc.M,user_pc.M,DIFFERENT_NONZERO_PATTERN);
> > KSPSetFromOptions(user_pc.block_solver);
> >
> >
> > I am running on solaris64.
> >
> > With best regards, Shaman Mahmoudi
> >
> >
>
>