Barry Smith schrieb: > > Run with GMRES, what happens? Same behaviour...
> > On Jun 4, 2009, at 11:07 AM, Andreas Grassl wrote: > >> Barry Smith schrieb: >>> >>> On Jun 3, 2009, at 5:29 PM, Andreas Grassl wrote: >>> >>>> Barry Smith schrieb: >>>>> >>>>> When properly running nn-cg (are you sure everything is symmetric?) >>>>> should require 10-30 iterations (certainly for model problems) >>>> >>>> ok, this was the number I expected. >>>> >>>>> >>>>>> nn-cg on 2 nodes 229 iterations, condition 6285 >>>>>> nn-cg on 4 nodes 331 iterations, condition 13312 >>>>> >>>>> Are you sure that your operator has the null space of only constants? >>>> >>>> no, I didn't touch anything regarding the null space since I thought >>>> it would be >>>> done inside the NN-preconditioner. Does this mean I have to set up a >>>> null space >>>> of the size of the Schur complement system, i.e. the number of >>>> interface DOF's? >>> >>> No, I don't think you need to do anything about the null space. The >>> code in PETSc for NN is for (and only for) a null space of constants. >>> BTW: with 2 or 4 subdomains they all touch the boundary and likely don't >>> have a null space anyways. >>> >>> Run with -ksp_view and make sure the local solves are being done with LU >>> >> >> I don't find the anomalies... setting local_ksp-rtol to 1e-8 doesn't >> change anything >> >> the options passed are: >> >> -is_localD_ksp_type preonly >> -is_localD_pc_factor_shift_positive_definite >> -is_localD_pc_type lu >> -is_localN_ksp_type preonly >> -is_localN_pc_factor_shift_positive_definite >> -is_localN_pc_type lu >> -ksp_rtol 1e-8 >> -ksp_view >> #-is_localD_ksp_view >> #-is_localN_ksp_view >> #-nn_coarse_ksp_view >> # -pc_is_remove_nullspace_fixed this option doesn't produce any effect >> -log_summary >> -options_left >> >> and produce: >> >> -ksp_view: >> >> KSP Object: >> type: cg >> maximum iterations=10000 >> tolerances: relative=1e-08, absolute=1e-50, divergence=10000 >> left preconditioning >> PC Object: >> type: nn >> linear system matrix = precond matrix: >> Matrix Object: >> type=is, rows=28632, cols=28632 >> Matrix Object:(is) >> type=seqaij, rows=7537, cols=7537 >> total: nonzeros=359491, allocated nonzeros=602960 >> using I-node routines: found 4578 nodes, limit used is 5 >> Matrix Object:(is) >> type=seqaij, rows=7515, cols=7515 >> total: nonzeros=349347, allocated nonzeros=601200 >> using I-node routines: found 5159 nodes, limit used is 5 >> Matrix Object:(is) >> type=seqaij, rows=7533, cols=7533 >> total: nonzeros=357291, allocated nonzeros=602640 >> using I-node routines: found 4739 nodes, limit used is 5 >> Matrix Object:(is) >> type=seqaij, rows=7360, cols=7360 >> total: nonzeros=364390, allocated nonzeros=588800 >> using I-node routines: found 3602 nodes, limit used is 5 >> >> -is_local...: >> >> KSP Object:(is_localD_) >> type: preonly >> maximum iterations=10000, initial guess is zero >> tolerances: relative=1e-05, absolute=1e-50, divergence=10000 >> left preconditioning >> PC Object:(is_localD_) >> type: lu >> LU: out-of-place factorization >> matrix ordering: nd >> LU: tolerance for zero pivot 1e-12 >> LU: using Manteuffel shift >> LU: factor fill ratio needed 4.73566 >> Factored matrix follows >> Matrix Object: >> type=seqaij, rows=6714, cols=6714 >> package used to perform factorization: petsc >> total: nonzeros=1479078, allocated nonzeros=1479078 >> using I-node routines: found 2790 nodes, limit used is 5 >> linear system matrix = precond matrix: >> Matrix Object: >> type=seqaij, rows=6714, cols=6714 >> total: nonzeros=312328, allocated nonzeros=312328 >> using I-node routines: found 4664 nodes, limit used is 5 >> >> KSP Object:(is_localN_) >> type: preonly >> maximum iterations=10000, initial guess is zero >> tolerances: relative=1e-05, absolute=1e-50, divergence=10000 >> left preconditioning >> PC Object:(is_localN_) >> type: lu >> LU: out-of-place factorization >> matrix ordering: nd >> LU: tolerance for zero pivot 1e-12 >> LU: using Manteuffel shift >> LU: factor fill ratio needed 5.07571 >> Factored matrix follows >> Matrix Object: >> type=seqaij, rows=7537, cols=7537 >> package used to perform factorization: petsc >> total: nonzeros=1824671, allocated nonzeros=1824671 >> using I-node routines: found 2939 nodes, limit used is 5 >> linear system matrix = precond matrix: >> Matrix Object:(is) >> type=seqaij, rows=7537, cols=7537 >> total: nonzeros=359491, allocated nonzeros=602960 >> using I-node routines: found 4578 nodes, limit used is 5 >> >> >> -nn_coarse_ksp_view: >> >> KSP Object:(nn_coarse_) >> type: preonly >> maximum iterations=10000, initial guess is zero >> tolerances: relative=1e-05, absolute=1e-50, divergence=10000 >> left preconditioning >> PC Object:(nn_coarse_) >> type: redundant >> Redundant preconditioner: First (color=0) of 4 PCs follows >> KSP Object:(redundant_) >> type: preonly >> maximum iterations=10000, initial guess is zero >> tolerances: relative=1e-05, absolute=1e-50, divergence=10000 >> left preconditioning >> PC Object:(redundant_) >> type: lu >> LU: out-of-place factorization >> matrix ordering: nd >> LU: tolerance for zero pivot 1e-12 >> LU: factor fill ratio needed 1 >> Factored matrix follows >> Matrix Object: >> type=seqaij, rows=4, cols=4 >> package used to perform factorization: petsc >> total: nonzeros=4, allocated nonzeros=4 >> not using I-node routines >> linear system matrix = precond matrix: >> Matrix Object: >> type=seqaij, rows=4, cols=4 >> total: nonzeros=4, allocated nonzeros=4 >> not using I-node routines >> linear system matrix = precond matrix: >> Matrix Object: >> type=mpiaij, rows=4, cols=4 >> total: nonzeros=4, allocated nonzeros=68 >> not using I-node (on process 0) routines >> >> >> cheers, >> >> ando >> >> -- >> /"\ Grassl Andreas >> \ / ASCII Ribbon Campaign Uni Innsbruck Institut f. 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