[petsc-users] CG with right preconditioning supports NONE norm type only
Matthew Knepley
knepley at gmail.com
Wed Mar 8 11:19:15 CST 2017
On Wed, Mar 8, 2017 at 10:47 AM, Kong, Fande <fande.kong at inl.gov> wrote:
> Thanks Barry,
>
> We are using "KSPSetPCSide(ksp, pcside)" in the code. I just tried
> "-ksp_pc_side right", and petsc did not error out.
>
> I like to understand why CG does not work with right preconditioning?
> Mathematically, the right preconditioning does not make sense?
>
cd src/snes/examples/tutorials
knepley/feature-plasma-example
$:/PETSc3/petsc/petsc-dev/src/snes/examples/tutorials$ ./ex5 -ksp_view
-ksp_type cg -ksp_pc_side right -ksp_error_if_not_converged
KSP Object: 1 MPI processes
type: cg
maximum iterations=10000, initial guess is zero
tolerances: relative=1e-05, absolute=1e-50, divergence=10000.
right preconditioning
using NONE norm type for convergence test
PC Object: 1 MPI processes
type: ilu
out-of-place factorization
0 levels of fill
tolerance for zero pivot 2.22045e-14
matrix ordering: natural
factor fill ratio given 1., needed 1.
Factored matrix follows:
Mat Object: 1 MPI processes
type: seqaij
rows=16, cols=16
package used to perform factorization: petsc
total: nonzeros=64, allocated nonzeros=64
total number of mallocs used during MatSetValues calls =0
not using I-node routines
linear system matrix = precond matrix:
Mat Object: 1 MPI processes
type: seqaij
rows=16, cols=16
total: nonzeros=64, allocated nonzeros=64
total number of mallocs used during MatSetValues calls =0
not using I-node routines
[0]PETSC ERROR: --------------------- Error Message
--------------------------------------------------------------
[0]PETSC ERROR:
[0]PETSC ERROR: KSPSolve has not converged
[0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html for
trouble shooting.
[0]PETSC ERROR: Petsc Development GIT revision: v3.7.5-3127-ge9f6087 GIT
Date: 2017-02-11 13:06:34 -0600
[0]PETSC ERROR: ./ex5 on a arch-c-exodus-master named
MATTHEW-KNEPLEYs-MacBook-Air-2.local by knepley Wed Mar 8 11:17:43 2017
[0]PETSC ERROR: Configure options --PETSC_ARCH=arch-c-exodus-master
--download-chaco --download-cmake --download-ctetgen --download-eigen
--download-exodusii --download-gmp --download-hdf5 --download-metis
--download-mpfr --download-mpich --download-netcdf --download-p4est
--download-parmetis --download-pragmatic --download-triangle --useThreads=1
--with-cc="/Users/knepley/MacSoftware/bin/ccache gcc -Qunused-arguments"
--with-cxx="/Users/knepley/MacSoftware/bin/ccache g++ -Qunused-arguments"
--with-fc="/Users/knepley/MacSoftware/bin/ccache gfortran"
--with-shared-libraries
[0]PETSC ERROR: #1 KSPSolve() line 847 in
/PETSc3/petsc/petsc-dev/src/ksp/ksp/interface/itfunc.c
[0]PETSC ERROR: #2 SNESSolve_NEWTONLS() line 224 in
/PETSc3/petsc/petsc-dev/src/snes/impls/ls/ls.c
[0]PETSC ERROR: #3 SNESSolve() line 3967 in
/PETSc3/petsc/petsc-dev/src/snes/interface/snes.c
[0]PETSC ERROR: #4 main() line 187 in
/PETSc3/petsc/petsc-dev/src/snes/examples/tutorials/ex5.c
[0]PETSC ERROR: PETSc Option Table entries:
[0]PETSC ERROR: -ksp_error_if_not_converged
[0]PETSC ERROR: -ksp_pc_side right
[0]PETSC ERROR: -ksp_type cg
[0]PETSC ERROR: -ksp_view
[0]PETSC ERROR: -malloc_test
[0]PETSC ERROR: ----------------End of Error Message -------send entire
error message to petsc-maint at mcs.anl.gov----------
So we are not getting an error
Matt
>
> Fande,
>
> On Wed, Mar 8, 2017 at 9:33 AM, Barry Smith <bsmith at mcs.anl.gov> wrote:
>
>>
>> Please tell us how you got this output.
>>
>> PETSc CG doesn't even implement right preconditioning. If you ask for
>> it it should error out. CG supports no norm computation with left
>> preconditioning.
>>
>> Barry
>>
>> > On Mar 8, 2017, at 10:26 AM, Kong, Fande <fande.kong at inl.gov> wrote:
>> >
>> > Hi All,
>> >
>> > The NONE norm type is supported only when CG is used with a right
>> preconditioner. Any reason for this?
>> >
>> >
>> >
>> > 0 Nonlinear |R| = 1.732051e+00
>> > 0 Linear |R| = 0.000000e+00
>> > 1 Linear |R| = 0.000000e+00
>> > 2 Linear |R| = 0.000000e+00
>> > 3 Linear |R| = 0.000000e+00
>> > 4 Linear |R| = 0.000000e+00
>> > 5 Linear |R| = 0.000000e+00
>> > 6 Linear |R| = 0.000000e+00
>> > 1 Nonlinear |R| = 1.769225e-08
>> > 0 Linear |R| = 0.000000e+00
>> > 1 Linear |R| = 0.000000e+00
>> > 2 Linear |R| = 0.000000e+00
>> > 3 Linear |R| = 0.000000e+00
>> > 4 Linear |R| = 0.000000e+00
>> > 5 Linear |R| = 0.000000e+00
>> > 6 Linear |R| = 0.000000e+00
>> > 7 Linear |R| = 0.000000e+00
>> > 8 Linear |R| = 0.000000e+00
>> > 9 Linear |R| = 0.000000e+00
>> > 10 Linear |R| = 0.000000e+00
>> > 2 Nonlinear |R| = 0.000000e+00
>> > SNES Object: 1 MPI processes
>> > type: newtonls
>> > maximum iterations=50, maximum function evaluations=10000
>> > tolerances: relative=1e-08, absolute=1e-50, solution=1e-50
>> > total number of linear solver iterations=18
>> > total number of function evaluations=23
>> > norm schedule ALWAYS
>> > SNESLineSearch Object: 1 MPI processes
>> > type: bt
>> > interpolation: cubic
>> > alpha=1.000000e-04
>> > maxstep=1.000000e+08, minlambda=1.000000e-12
>> > tolerances: relative=1.000000e-08, absolute=1.000000e-15,
>> lambda=1.000000e-08
>> > maximum iterations=40
>> > KSP Object: 1 MPI processes
>> > type: cg
>> > maximum iterations=10000, initial guess is zero
>> > tolerances: relative=1e-05, absolute=1e-50, divergence=10000.
>> > right preconditioning
>> > using NONE norm type for convergence test
>> > PC Object: 1 MPI processes
>> > type: hypre
>> > HYPRE BoomerAMG preconditioning
>> > HYPRE BoomerAMG: Cycle type V
>> > HYPRE BoomerAMG: Maximum number of levels 25
>> > HYPRE BoomerAMG: Maximum number of iterations PER hypre call 1
>> > HYPRE BoomerAMG: Convergence tolerance PER hypre call 0.
>> > HYPRE BoomerAMG: Threshold for strong coupling 0.25
>> > HYPRE BoomerAMG: Interpolation truncation factor 0.
>> > HYPRE BoomerAMG: Interpolation: max elements per row 0
>> > HYPRE BoomerAMG: Number of levels of aggressive coarsening 0
>> > HYPRE BoomerAMG: Number of paths for aggressive coarsening 1
>> > HYPRE BoomerAMG: Maximum row sums 0.9
>> > HYPRE BoomerAMG: Sweeps down 1
>> > HYPRE BoomerAMG: Sweeps up 1
>> > HYPRE BoomerAMG: Sweeps on coarse 1
>> > HYPRE BoomerAMG: Relax down symmetric-SOR/Jacobi
>> > HYPRE BoomerAMG: Relax up symmetric-SOR/Jacobi
>> > HYPRE BoomerAMG: Relax on coarse Gaussian-elimination
>> > HYPRE BoomerAMG: Relax weight (all) 1.
>> > HYPRE BoomerAMG: Outer relax weight (all) 1.
>> > HYPRE BoomerAMG: Using CF-relaxation
>> > HYPRE BoomerAMG: Not using more complex smoothers.
>> > HYPRE BoomerAMG: Measure type local
>> > HYPRE BoomerAMG: Coarsen type Falgout
>> > HYPRE BoomerAMG: Interpolation type classical
>> > linear system matrix followed by preconditioner matrix:
>> > Mat Object: 1 MPI processes
>> > type: mffd
>> > rows=9, cols=9
>> > Matrix-free approximation:
>> > err=1.49012e-08 (relative error in function evaluation)
>> > Using wp compute h routine
>> > Does not compute normU
>> > Mat Object: () 1 MPI processes
>> > type: seqaij
>> > rows=9, cols=9
>> > total: nonzeros=49, allocated nonzeros=49
>> > total number of mallocs used during MatSetValues calls =0
>> > not using I-node routines
>> >
>> > Fande,
>> >
>>
>>
>
--
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
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