Thank you for your reply.
I set the relative tolerance of 1e-10, below is the output with
ksp_monitor_true_residual,
step 1 (converged):
0 KSP unpreconditioned resid norm 5.853072011788e-01 true resid norm
5.853072011788e-01 ||r(i)||/||b|| 1.000000000000e+00
1 KSP unpreconditioned resid norm 1.263467051263e-02 true resid norm
1.263467051263e-02 ||r(i)||/||b|| 2.158639170539e-02
2 KSP unpreconditioned resid norm 1.341051880494e-03 true resid norm
1.341051880494e-03 ||r(i)||/||b|| 2.291193202122e-03
3 KSP unpreconditioned resid norm 5.281711107599e-04 true resid norm
5.281711107599e-04 ||r(i)||/||b|| 9.023827311473e-04
4 KSP unpreconditioned resid norm 2.265161267248e-04 true resid norm
2.265161267248e-04 ||r(i)||/||b|| 3.870038268256e-04
5 KSP unpreconditioned resid norm 6.083108409953e-05 true resid norm
6.083108409954e-05 ||r(i)||/||b|| 1.039301822650e-04
6 KSP unpreconditioned resid norm 2.049038801905e-05 true resid norm
2.049038801906e-05 ||r(i)||/||b|| 3.500792058903e-05
7 KSP unpreconditioned resid norm 4.908575378578e-06 true resid norm
4.908575378575e-06 ||r(i)||/||b|| 8.386323231099e-06
8 KSP unpreconditioned resid norm 1.160371295964e-06 true resid norm
1.160371295960e-06 ||r(i)||/||b|| 1.982499606399e-06
9 KSP unpreconditioned resid norm 2.993349323170e-07 true resid norm
2.993349323154e-07 ||r(i)||/||b|| 5.114150854671e-07
10 KSP unpreconditioned resid norm 6.423860393220e-08 true resid norm
6.423860392241e-08 ||r(i)||/||b|| 1.097519452913e-07
11 KSP unpreconditioned resid norm 1.486343352971e-08 true resid norm
1.486343352542e-08 ||r(i)||/||b|| 2.539424339131e-08
12 KSP unpreconditioned resid norm 3.388518888745e-09 true resid norm
3.388518889406e-09 ||r(i)||/||b|| 5.789299845588e-09
13 KSP unpreconditioned resid norm 8.414456498118e-10 true resid norm
8.414456551004e-10 ||r(i)||/||b|| 1.437613706795e-09
14 KSP unpreconditioned resid norm 2.052670281766e-10 true resid norm
2.052670332352e-10 ||r(i)||/||b|| 3.506996545092e-10
15 KSP unpreconditioned resid norm 4.739342260680e-11 true resid norm
4.739342219912e-11 ||r(i)||/||b|| 8.097187614243e-11
Linear solve converged due to CONVERGED_RTOL iterations 15
KSP Object: 1 MPI processes
type: fgmres
restart=30, using Classical (unmodified) Gram-Schmidt
Orthogonalization with no iterative refinement
happy breakdown tolerance 1e-30
maximum iterations=10000, nonzero initial guess
tolerances: relative=1e-10, absolute=1e-50, divergence=10000.
right preconditioning
using UNPRECONDITIONED norm type for convergence test
PC Object: 1 MPI processes
type: fieldsplit
FieldSplit with Schur preconditioner, factorization FULL
Preconditioner for the Schur complement formed from Sp, an assembled
approximation to S, which uses A00's diagonal's inverse
Split info:
Split number 0 Defined by IS
Split number 1 Defined by IS
KSP solver for A00 block
KSP Object: (fieldsplit_0_) 1 MPI processes
type: preonly
maximum iterations=10000, initial guess is zero
tolerances: relative=1e-05, absolute=1e-50, divergence=10000.
left preconditioning
using NONE norm type for convergence test
PC Object: (fieldsplit_0_) 1 MPI processes
type: hypre
HYPRE BoomerAMG preconditioning
Cycle type V
Maximum number of levels 25
Maximum number of iterations PER hypre call 1
Convergence tolerance PER hypre call 0.
Threshold for strong coupling 0.25
Interpolation truncation factor 0.
Interpolation: max elements per row 0
Number of levels of aggressive coarsening 0
Number of paths for aggressive coarsening 1
Maximum row sums 0.9
Sweeps down 1
Sweeps up 1
Sweeps on coarse 1
Relax down symmetric-SOR/Jacobi
Relax up symmetric-SOR/Jacobi
Relax on coarse Gaussian-elimination
Relax weight (all) 1.
Outer relax weight (all) 1.
Using CF-relaxation
Not using more complex smoothers.
Measure type local
Coarsen type Falgout
Interpolation type classical
linear system matrix = precond matrix:
Mat Object: (fieldsplit_0_) 1 MPI processes
type: seqaij
rows=28578, cols=28578
total: nonzeros=653916, allocated nonzeros=653916
total number of mallocs used during MatSetValues calls =0
not using I-node routines
KSP solver for S = A11 - A10 inv(A00) A01
KSP Object: (fieldsplit_1_) 1 MPI processes
type: preonly
maximum iterations=10000, initial guess is zero
tolerances: relative=1e-05, absolute=1e-50, divergence=10000.
left preconditioning
using NONE norm type for convergence test
PC Object: (fieldsplit_1_) 1 MPI processes
type: hypre
HYPRE BoomerAMG preconditioning
Cycle type V
Maximum number of levels 25
Maximum number of iterations PER hypre call 1
Convergence tolerance PER hypre call 0.
Threshold for strong coupling 0.25
Interpolation truncation factor 0.
Interpolation: max elements per row 0
Number of levels of aggressive coarsening 0
Number of paths for aggressive coarsening 1
Maximum row sums 0.9
Sweeps down 1
Sweeps up 1
Sweeps on coarse 1
Relax down symmetric-SOR/Jacobi
Relax up symmetric-SOR/Jacobi
Relax on coarse Gaussian-elimination
Relax weight (all) 1.
Outer relax weight (all) 1.
Using CF-relaxation
Not using more complex smoothers.
Measure type local
Coarsen type Falgout
Interpolation type classical
linear system matrix followed by preconditioner matrix:
Mat Object: (fieldsplit_1_) 1 MPI processes
type: schurcomplement
rows=3874, cols=3874
Schur complement A11 - A10 inv(A00) A01
A11
Mat Object: (fieldsplit_1_) 1 MPI processes
type: seqaij
rows=3874, cols=3874
total: nonzeros=0, allocated nonzeros=0
total number of mallocs used during MatSetValues calls
=0
using I-node routines: found 775 nodes, limit used is
5
A10
Mat Object: 1 MPI processes
type: seqaij
rows=3874, cols=28578
total: nonzeros=138180, allocated nonzeros=138180
total number of mallocs used during MatSetValues calls
=0
not using I-node routines
KSP of A00
KSP Object: (fieldsplit_0_) 1 MPI processes
type: preonly
maximum iterations=10000, initial guess is zero
tolerances: relative=1e-05, absolute=1e-50,
divergence=10000.
left preconditioning
using NONE norm type for convergence test
PC Object: (fieldsplit_0_) 1 MPI processes
type: hypre
HYPRE BoomerAMG preconditioning
Cycle type V
Maximum number of levels 25
Maximum number of iterations PER hypre call 1
Convergence tolerance PER hypre call 0.
Threshold for strong coupling 0.25
Interpolation truncation factor 0.
Interpolation: max elements per row 0
Number of levels of aggressive coarsening 0
Number of paths for aggressive coarsening 1
Maximum row sums 0.9
Sweeps down 1
Sweeps up 1
Sweeps on coarse 1
Relax down symmetric-SOR/Jacobi
Relax up symmetric-SOR/Jacobi
Relax on coarse Gaussian-elimination
Relax weight (all) 1.
Outer relax weight (all) 1.
Using CF-relaxation
Not using more complex smoothers.
Measure type local
Coarsen type Falgout
Interpolation type classical
linear system matrix = precond matrix:
Mat Object: (fieldsplit_0_) 1 MPI processes
type: seqaij
rows=28578, cols=28578
total: nonzeros=653916, allocated nonzeros=653916
total number of mallocs used during MatSetValues calls
=0
not using I-node routines
A01
Mat Object: 1 MPI processes
type: seqaij
rows=28578, cols=3874
total: nonzeros=138180, allocated nonzeros=138180
total number of mallocs used during MatSetValues calls
=0
not using I-node routines
Mat Object: 1 MPI processes
type: seqaij
rows=3874, cols=3874
total: nonzeros=77704, allocated nonzeros=77704
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: nest
rows=32452, cols=32452
Matrix object:
type=nest, rows=2, cols=2
MatNest structure:
(0,0) : prefix="fieldsplit_0_", type=seqaij, rows=28578,
cols=28578
(0,1) : type=seqaij, rows=28578, cols=3874
(1,0) : type=seqaij, rows=3874, cols=28578
(1,1) : prefix="fieldsplit_1_", type=seqaij, rows=3874,
cols=3874
step 2 (NOT converged):
Linear solve did not converge due to DIVERGED_NANORINF iterations 0
KSP Object: 1 MPI processes
type: fgmres
restart=30, using Classical (unmodified) Gram-Schmidt
Orthogonalization with no iterative refinement
happy breakdown tolerance 1e-30
maximum iterations=10000, nonzero initial guess
tolerances: relative=1e-10, absolute=1e-50, divergence=10000.
right preconditioning
using UNPRECONDITIONED norm type for convergence test
PC Object: 1 MPI processes
type: fieldsplit
FieldSplit with Schur preconditioner, factorization FULL
Preconditioner for the Schur complement formed from Sp, an assembled
approximation to S, which uses A00's diagonal's inverse
Split info:
Split number 0 Defined by IS
Split number 1 Defined by IS
KSP solver for A00 block
KSP Object: (fieldsplit_0_) 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: (fieldsplit_0_) 1 MPI processes
type: hypre
PC has not been set up so information may be incomplete
HYPRE BoomerAMG preconditioning
Cycle type V
Maximum number of levels 25
Maximum number of iterations PER hypre call 1
Convergence tolerance PER hypre call 0.
Threshold for strong coupling 0.25
Interpolation truncation factor 0.
Interpolation: max elements per row 0
Number of levels of aggressive coarsening 0
Number of paths for aggressive coarsening 1
Maximum row sums 0.9
Sweeps down 1
Sweeps up 1
Sweeps on coarse 1
Relax down symmetric-SOR/Jacobi
Relax up symmetric-SOR/Jacobi
Relax on coarse Gaussian-elimination
Relax weight (all) 1.
Outer relax weight (all) 1.
Using CF-relaxation
Not using more complex smoothers.
Measure type local
Coarsen type Falgout
Interpolation type classical
linear system matrix = precond matrix:
Mat Object: (fieldsplit_0_) 1 MPI processes
type: seqaij
rows=28578, cols=28578
total: nonzeros=653916, allocated nonzeros=653916
total number of mallocs used during MatSetValues calls =0
not using I-node routines
KSP solver for S = A11 - A10 inv(A00) A01
KSP Object: (fieldsplit_1_) 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: (fieldsplit_1_) 1 MPI processes
type: hypre
PC has not been set up so information may be incomplete
HYPRE BoomerAMG preconditioning
Cycle type V
Maximum number of levels 25
Maximum number of iterations PER hypre call 1
Convergence tolerance PER hypre call 0.
Threshold for strong coupling 0.25
Interpolation truncation factor 0.
Interpolation: max elements per row 0
Number of levels of aggressive coarsening 0
Number of paths for aggressive coarsening 1
Maximum row sums 0.9
Sweeps down 1
Sweeps up 1
Sweeps on coarse 1
Relax down symmetric-SOR/Jacobi
Relax up symmetric-SOR/Jacobi
Relax on coarse Gaussian-elimination
Relax weight (all) 1.
Outer relax weight (all) 1.
Using CF-relaxation
Not using more complex smoothers.
Measure type local
Coarsen type Falgout
Interpolation type classical
linear system matrix followed by preconditioner matrix:
Mat Object: (fieldsplit_1_) 1 MPI processes
type: schurcomplement
rows=3874, cols=3874
Schur complement A11 - A10 inv(A00) A01
A11
Mat Object: (fieldsplit_1_) 1 MPI processes
type: seqaij
rows=3874, cols=3874
total: nonzeros=0, allocated nonzeros=0
total number of mallocs used during MatSetValues calls
=0
using I-node routines: found 775 nodes, limit used is
5
A10
Mat Object: 1 MPI processes
type: seqaij
rows=3874, cols=28578
total: nonzeros=138180, allocated nonzeros=138180
total number of mallocs used during MatSetValues calls
=0
not using I-node routines
KSP of A00
KSP Object: (fieldsplit_0_) 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: (fieldsplit_0_) 1 MPI processes
type: hypre
PC has not been set up so information may be incomplete
HYPRE BoomerAMG preconditioning
Cycle type V
Maximum number of levels 25
Maximum number of iterations PER hypre call 1
Convergence tolerance PER hypre call 0.
Threshold for strong coupling 0.25
Interpolation truncation factor 0.
Interpolation: max elements per row 0
Number of levels of aggressive coarsening 0
Number of paths for aggressive coarsening 1
Maximum row sums 0.9
Sweeps down 1
Sweeps up 1
Sweeps on coarse 1
Relax down symmetric-SOR/Jacobi
Relax up symmetric-SOR/Jacobi
Relax on coarse Gaussian-elimination
Relax weight (all) 1.
Outer relax weight (all) 1.
Using CF-relaxation
Not using more complex smoothers.
Measure type local
Coarsen type Falgout
Interpolation type classical
linear system matrix = precond matrix:
Mat Object: (fieldsplit_0_) 1 MPI processes
type: seqaij
rows=28578, cols=28578
total: nonzeros=653916, allocated nonzeros=653916
total number of mallocs used during MatSetValues calls
=0
not using I-node routines
A01
Mat Object: 1 MPI processes
type: seqaij
rows=28578, cols=3874
total: nonzeros=138180, allocated nonzeros=138180
total number of mallocs used during MatSetValues calls
=0
not using I-node routines
Mat Object: 1 MPI processes
type: seqaij
rows=3874, cols=3874
total: nonzeros=77704, allocated nonzeros=77704
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: nest
rows=32452, cols=32452
Matrix object:
type=nest, rows=2, cols=2
MatNest structure:
(0,0) : prefix="fieldsplit_0_", type=seqaij, rows=28578,
cols=28578
(0,1) : type=seqaij, rows=28578, cols=3874
(1,0) : type=seqaij, rows=3874, cols=28578
(1,1) : prefix="fieldsplit_1_", type=seqaij, rows=3874,
cols=3874
HOWEVER, if I do not use -ksp_monitor_true_residual, both two
steps converge.
step 1:
Linear solve converged due to CONVERGED_RTOL iterations 15
KSP Object: 1 MPI processes
type: fgmres
restart=30, using Classical (unmodified) Gram-Schmidt
Orthogonalization with no iterative refinement
happy breakdown tolerance 1e-30
maximum iterations=10000, nonzero initial guess
tolerances: relative=1e-10, absolute=1e-50, divergence=10000.
right preconditioning
using UNPRECONDITIONED norm type for convergence test
PC Object: 1 MPI processes
type: fieldsplit
FieldSplit with Schur preconditioner, factorization FULL
Preconditioner for the Schur complement formed from Sp, an assembled
approximation to S, which uses A00's diagonal's inverse
Split info:
Split number 0 Defined by IS
Split number 1 Defined by IS
KSP solver for A00 block
KSP Object: (fieldsplit_0_) 1 MPI processes
type: preonly
maximum iterations=10000, initial guess is zero
tolerances: relative=1e-05, absolute=1e-50, divergence=10000.
left preconditioning
using NONE norm type for convergence test
PC Object: (fieldsplit_0_) 1 MPI processes
type: hypre
HYPRE BoomerAMG preconditioning
Cycle type V
Maximum number of levels 25
Maximum number of iterations PER hypre call 1
Convergence tolerance PER hypre call 0.
Threshold for strong coupling 0.25
Interpolation truncation factor 0.
Interpolation: max elements per row 0
Number of levels of aggressive coarsening 0
Number of paths for aggressive coarsening 1
Maximum row sums 0.9
Sweeps down 1
Sweeps up 1
Sweeps on coarse 1
Relax down symmetric-SOR/Jacobi
Relax up symmetric-SOR/Jacobi
Relax on coarse Gaussian-elimination
Relax weight (all) 1.
Outer relax weight (all) 1.
Using CF-relaxation
Not using more complex smoothers.
Measure type local
Coarsen type Falgout
Interpolation type classical
linear system matrix = precond matrix:
Mat Object: (fieldsplit_0_) 1 MPI processes
type: seqaij
rows=28578, cols=28578
total: nonzeros=653916, allocated nonzeros=653916
total number of mallocs used during MatSetValues calls =0
not using I-node routines
KSP solver for S = A11 - A10 inv(A00) A01
KSP Object: (fieldsplit_1_) 1 MPI processes
type: preonly
maximum iterations=10000, initial guess is zero
tolerances: relative=1e-05, absolute=1e-50, divergence=10000.
left preconditioning
using NONE norm type for convergence test
PC Object: (fieldsplit_1_) 1 MPI processes
type: hypre
HYPRE BoomerAMG preconditioning
Cycle type V
Maximum number of levels 25
Maximum number of iterations PER hypre call 1
Convergence tolerance PER hypre call 0.
Threshold for strong coupling 0.25
Interpolation truncation factor 0.
Interpolation: max elements per row 0
Number of levels of aggressive coarsening 0
Number of paths for aggressive coarsening 1
Maximum row sums 0.9
Sweeps down 1
Sweeps up 1
Sweeps on coarse 1
Relax down symmetric-SOR/Jacobi
Relax up symmetric-SOR/Jacobi
Relax on coarse Gaussian-elimination
Relax weight (all) 1.
Outer relax weight (all) 1.
Using CF-relaxation
Not using more complex smoothers.
Measure type local
Coarsen type Falgout
Interpolation type classical
linear system matrix followed by preconditioner matrix:
Mat Object: (fieldsplit_1_) 1 MPI processes
type: schurcomplement
rows=3874, cols=3874
Schur complement A11 - A10 inv(A00) A01
A11
Mat Object: (fieldsplit_1_) 1 MPI processes
type: seqaij
rows=3874, cols=3874
total: nonzeros=0, allocated nonzeros=0
total number of mallocs used during MatSetValues calls
=0
using I-node routines: found 775 nodes, limit used is
5
A10
Mat Object: 1 MPI processes
type: seqaij
rows=3874, cols=28578
total: nonzeros=138180, allocated nonzeros=138180
total number of mallocs used during MatSetValues calls
=0
not using I-node routines
KSP of A00
KSP Object: (fieldsplit_0_) 1 MPI processes
type: preonly
maximum iterations=10000, initial guess is zero
tolerances: relative=1e-05, absolute=1e-50,
divergence=10000.
left preconditioning
using NONE norm type for convergence test
PC Object: (fieldsplit_0_) 1 MPI processes
type: hypre
HYPRE BoomerAMG preconditioning
Cycle type V
Maximum number of levels 25
Maximum number of iterations PER hypre call 1
Convergence tolerance PER hypre call 0.
Threshold for strong coupling 0.25
Interpolation truncation factor 0.
Interpolation: max elements per row 0
Number of levels of aggressive coarsening 0
Number of paths for aggressive coarsening 1
Maximum row sums 0.9
Sweeps down 1
Sweeps up 1
Sweeps on coarse 1
Relax down symmetric-SOR/Jacobi
Relax up symmetric-SOR/Jacobi
Relax on coarse Gaussian-elimination
Relax weight (all) 1.
Outer relax weight (all) 1.
Using CF-relaxation
Not using more complex smoothers.
Measure type local
Coarsen type Falgout
Interpolation type classical
linear system matrix = precond matrix:
Mat Object: (fieldsplit_0_) 1 MPI processes
type: seqaij
rows=28578, cols=28578
total: nonzeros=653916, allocated nonzeros=653916
total number of mallocs used during MatSetValues calls
=0
not using I-node routines
A01
Mat Object: 1 MPI processes
type: seqaij
rows=28578, cols=3874
total: nonzeros=138180, allocated nonzeros=138180
total number of mallocs used during MatSetValues calls
=0
not using I-node routines
Mat Object: 1 MPI processes
type: seqaij
rows=3874, cols=3874
total: nonzeros=77704, allocated nonzeros=77704
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: nest
rows=32452, cols=32452
Matrix object:
type=nest, rows=2, cols=2
MatNest structure:
(0,0) : prefix="fieldsplit_0_", type=seqaij, rows=28578,
cols=28578
(0,1) : type=seqaij, rows=28578, cols=3874
(1,0) : type=seqaij, rows=3874, cols=28578
(1,1) : prefix="fieldsplit_1_", type=seqaij, rows=3874,
cols=3874
step 2:
Linear solve converged due to CONVERGED_RTOL iterations 1
KSP Object: 1 MPI processes
type: fgmres
restart=30, using Classical (unmodified) Gram-Schmidt
Orthogonalization with no iterative refinement
happy breakdown tolerance 1e-30
maximum iterations=10000, nonzero initial guess
tolerances: relative=1e-10, absolute=1e-50, divergence=10000.
right preconditioning
using UNPRECONDITIONED norm type for convergence test
PC Object: 1 MPI processes
type: fieldsplit
FieldSplit with Schur preconditioner, factorization FULL
Preconditioner for the Schur complement formed from Sp, an assembled
approximation to S, which uses A00's diagonal's inverse
Split info:
Split number 0 Defined by IS
Split number 1 Defined by IS
KSP solver for A00 block
KSP Object: (fieldsplit_0_) 1 MPI processes
type: preonly
maximum iterations=10000, initial guess is zero
tolerances: relative=1e-05, absolute=1e-50, divergence=10000.
left preconditioning
using NONE norm type for convergence test
PC Object: (fieldsplit_0_) 1 MPI processes
type: hypre
HYPRE BoomerAMG preconditioning
Cycle type V
Maximum number of levels 25
Maximum number of iterations PER hypre call 1
Convergence tolerance PER hypre call 0.
Threshold for strong coupling 0.25
Interpolation truncation factor 0.
Interpolation: max elements per row 0
Number of levels of aggressive coarsening 0
Number of paths for aggressive coarsening 1
Maximum row sums 0.9
Sweeps down 1
Sweeps up 1
Sweeps on coarse 1
Relax down symmetric-SOR/Jacobi
Relax up symmetric-SOR/Jacobi
Relax on coarse Gaussian-elimination
Relax weight (all) 1.
Outer relax weight (all) 1.
Using CF-relaxation
Not using more complex smoothers.
Measure type local
Coarsen type Falgout
Interpolation type classical
linear system matrix = precond matrix:
Mat Object: (fieldsplit_0_) 1 MPI processes
type: seqaij
rows=28578, cols=28578
total: nonzeros=653916, allocated nonzeros=653916
total number of mallocs used during MatSetValues calls =0
not using I-node routines
KSP solver for S = A11 - A10 inv(A00) A01
KSP Object: (fieldsplit_1_) 1 MPI processes
type: preonly
maximum iterations=10000, initial guess is zero
tolerances: relative=1e-05, absolute=1e-50, divergence=10000.
left preconditioning
using NONE norm type for convergence test
PC Object: (fieldsplit_1_) 1 MPI processes
type: hypre
HYPRE BoomerAMG preconditioning
Cycle type V
Maximum number of levels 25
Maximum number of iterations PER hypre call 1
Convergence tolerance PER hypre call 0.
Threshold for strong coupling 0.25
Interpolation truncation factor 0.
Interpolation: max elements per row 0
Number of levels of aggressive coarsening 0
Number of paths for aggressive coarsening 1
Maximum row sums 0.9
Sweeps down 1
Sweeps up 1
Sweeps on coarse 1
Relax down symmetric-SOR/Jacobi
Relax up symmetric-SOR/Jacobi
Relax on coarse Gaussian-elimination
Relax weight (all) 1.
Outer relax weight (all) 1.
Using CF-relaxation
Not using more complex smoothers.
Measure type local
Coarsen type Falgout
Interpolation type classical
linear system matrix followed by preconditioner matrix:
Mat Object: (fieldsplit_1_) 1 MPI processes
type: schurcomplement
rows=3874, cols=3874
Schur complement A11 - A10 inv(A00) A01
A11
Mat Object: (fieldsplit_1_) 1 MPI processes
type: seqaij
rows=3874, cols=3874
total: nonzeros=0, allocated nonzeros=0
total number of mallocs used during MatSetValues calls
=0
using I-node routines: found 775 nodes, limit used is
5
A10
Mat Object: 1 MPI processes
type: seqaij
rows=3874, cols=28578
total: nonzeros=138180, allocated nonzeros=138180
total number of mallocs used during MatSetValues calls
=0
not using I-node routines
KSP of A00
KSP Object: (fieldsplit_0_) 1 MPI processes
type: preonly
maximum iterations=10000, initial guess is zero
tolerances: relative=1e-05, absolute=1e-50,
divergence=10000.
left preconditioning
using NONE norm type for convergence test
PC Object: (fieldsplit_0_) 1 MPI processes
type: hypre
HYPRE BoomerAMG preconditioning
Cycle type V
Maximum number of levels 25
Maximum number of iterations PER hypre call 1
Convergence tolerance PER hypre call 0.
Threshold for strong coupling 0.25
Interpolation truncation factor 0.
Interpolation: max elements per row 0
Number of levels of aggressive coarsening 0
Number of paths for aggressive coarsening 1
Maximum row sums 0.9
Sweeps down 1
Sweeps up 1
Sweeps on coarse 1
Relax down symmetric-SOR/Jacobi
Relax up symmetric-SOR/Jacobi
Relax on coarse Gaussian-elimination
Relax weight (all) 1.
Outer relax weight (all) 1.
Using CF-relaxation
Not using more complex smoothers.
Measure type local
Coarsen type Falgout
Interpolation type classical
linear system matrix = precond matrix:
Mat Object: (fieldsplit_0_) 1 MPI processes
type: seqaij
rows=28578, cols=28578
total: nonzeros=653916, allocated nonzeros=653916
total number of mallocs used during MatSetValues calls
=0
not using I-node routines
A01
Mat Object: 1 MPI processes
type: seqaij
rows=28578, cols=3874
total: nonzeros=138180, allocated nonzeros=138180
total number of mallocs used during MatSetValues calls
=0
not using I-node routines
Mat Object: 1 MPI processes
type: seqaij
rows=3874, cols=3874
total: nonzeros=77704, allocated nonzeros=77704
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: nest
rows=32452, cols=32452
Matrix object:
type=nest, rows=2, cols=2
MatNest structure:
(0,0) : prefix="fieldsplit_0_", type=seqaij, rows=28578,
cols=28578
(0,1) : type=seqaij, rows=28578, cols=3874
(1,0) : type=seqaij, rows=3874, cols=28578
(1,1) : prefix="fieldsplit_1_", type=seqaij, rows=3874,
cols=3874
Thank you for your help and time.
Kind regards,
Shidi
On 2020-06-05 13:40, Matthew Knepley wrote:
On Fri, Jun 5, 2020 at 7:42 AM Y. Shidi <ys...@cam.ac.uk> wrote:
This algebraic tolerance is strange. Why put it below unit
roundoff?
We are testing a static bubble problem, if the tolerance is 1e-10 it
won't approach static solution.
I do not understand. Every computation in your problem makes errors of
order 1e-15,
since that is the roundoff. Moreover, you cannot expect a solution to
be more accurate
than (condition number * roundoff). I would be surprised if the
condition number is near 1,
since you would not need a solver. So what is going on?
Thanks,
Matt
Thanks,
Shidi
On 2020-06-05 11:48, Matthew Knepley wrote:
On Fri, Jun 5, 2020 at 6:12 AM Y. Shidi <ys...@cam.ac.uk> wrote:
Dear developers,
We are using filed splitting method solve saddle point problem.
Below is our ksp configuration:
PetscOptionsSetValue(NULL,"-ksp_type","gmres");
PetscOptionsSetValue(NULL,"-ksp_initial_guess_nonzero","");
PetscOptionsSetValue(NULL,"-ksp_rtol","1e-20");
This algebraic tolerance is strange. Why put it below unit
roundoff?
PetscOptionsSetValue(NULL,"-ksp_converged_reason", "");
PetscOptionsSetValue(NULL,"-pc_type", "fieldsplit");
PetscOptionsSetValue(NULL,"-pc_fieldsplit_type", "schur");
PetscOptionsSetValue(NULL,"-pc_fieldsplit_schur_fact_type",
"lower");
PetscOptionsSetValue(NULL,"-pc_fieldsplit_schur_precondition",
"selfp");
PetscOptionsSetValue(NULL,"-fieldsplit_0_ksp_type", "preonly");
PetscOptionsSetValue(NULL,"-fieldsplit_0_pc_type", "hypre");
PetscOptionsSetValue(NULL,"-fieldsplit_1_ksp_type", "preonly");
PetscOptionsSetValue(NULL,"-fieldsplit_1_pc_type", "hypre");
It can be converged. However, when we turn on the ksp monitor:
PetscOptionsSetValue(NULL,"-ksp_monitor_true_residual", "");
It won't converge. It seems very odd, I am wondering why it
happens.
Can you try it with a relative tolerance of 1e-10, and send the
output
(with -ksp_view as well).
Thanks,
Matt
Thank you for your time and help.
Kind regards,
Shidi
--
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/ [1]
Links:
------
[1] http://www.cse.buffalo.edu/~knepley/
--
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/ [1]
Links:
------
[1] http://www.cse.buffalo.edu/~knepley/
