<div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">On Fri, Sep 5, 2014 at 1:34 AM, Klaij, Christiaan <span dir="ltr"><<a href="mailto:C.Klaij@marin.nl" target="_blank">C.Klaij@marin.nl</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
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Matt,<br>
<br>
I think the problem is somehow related to -pc_fieldsplit_schur_precondition selfp. In the example below your are not using that option.<br></div></div></blockquote><div><br></div><div>Here is the selfp output. It retains the A00 solver.</div><div><br></div><div>ex62 -run_type full -refinement_limit 0.00625 -bc_type dirichlet -interpolate 1 -vel_petscspace_order 2 -pres_petscspace_order 1 -ksp_type fgmres -ksp_gmres_restart 100 -ksp_rtol 1.0e-9 -pc_type fieldsplit -pc_fieldsplit_type schur -pc_fieldsplit_schur_factorization_type full -fieldsplit_pressure_ksp_rtol 1e-10 -fieldsplit_velocity_ksp_type gmres -fieldsplit_velocity_pc_type lu -fieldsplit_pressure_pc_type jacobi -snes_monitor_short -ksp_monitor_short -snes_converged_reason -ksp_converged_reason -snes_view -show_solution 0 -fieldsplit_pressure_inner_ksp_type preonly -fieldsplit_pressure_inner_pc_type jacobi -pc_fieldsplit_schur_precondition selfp<br></div><div><br></div><div><div>SNES Object: 1 MPI processes</div><div> type: newtonls</div><div> maximum iterations=50, maximum function evaluations=10000</div><div> tolerances: relative=1e-08, absolute=1e-50, solution=1e-08</div><div> total number of linear solver iterations=20</div><div> total number of function evaluations=2</div><div> SNESLineSearch Object: 1 MPI processes</div><div> type: bt</div><div> interpolation: cubic</div><div> alpha=1.000000e-04</div><div> maxstep=1.000000e+08, minlambda=1.000000e-12</div><div> tolerances: relative=1.000000e-08, absolute=1.000000e-15, lambda=1.000000e-08</div><div> maximum iterations=40</div><div> KSP Object: 1 MPI processes</div><div> type: fgmres</div><div> GMRES: restart=100, using Classical (unmodified) Gram-Schmidt Orthogonalization with no iterative refinement</div><div> GMRES: happy breakdown tolerance 1e-30</div><div> maximum iterations=10000, initial guess is zero</div><div> tolerances: relative=1e-09, absolute=1e-50, divergence=10000</div><div> right preconditioning</div><div> has attached null space</div><div> using UNPRECONDITIONED norm type for convergence test</div><div> PC Object: 1 MPI processes</div><div> type: fieldsplit</div><div> FieldSplit with Schur preconditioner, factorization FULL</div><div> Preconditioner for the Schur complement formed from Sp, an assembled approximation to S, which uses (the lumped) A00's diagonal's inverse</div><div> Split info:</div><div> Split number 0 Defined by IS</div><div> Split number 1 Defined by IS</div><div> KSP solver for A00 block</div><div> KSP Object: (fieldsplit_velocity_) 1 MPI processes</div><div> type: gmres</div><div> GMRES: restart=30, using Classical (unmodified) Gram-Schmidt Orthogonalization with no iterative refinement</div><div> GMRES: happy breakdown tolerance 1e-30</div><div> maximum iterations=10000, initial guess is zero</div><div> tolerances: relative=1e-05, absolute=1e-50, divergence=10000</div><div> left preconditioning</div><div> using PRECONDITIONED norm type for convergence test</div><div> PC Object: (fieldsplit_velocity_) 1 MPI processes</div><div> type: lu</div><div> LU: out-of-place factorization</div><div> tolerance for zero pivot 2.22045e-14</div><div> matrix ordering: nd</div><div> factor fill ratio given 5, needed 3.45047</div><div> Factored matrix follows:</div><div> Mat Object: 1 MPI processes</div><div> type: seqaij</div><div> rows=962, cols=962</div><div> package used to perform factorization: petsc</div><div> total: nonzeros=68692, allocated nonzeros=68692</div><div> total number of mallocs used during MatSetValues calls =0</div><div> using I-node routines: found 456 nodes, limit used is 5</div><div> linear system matrix = precond matrix:</div><div> Mat Object: (fieldsplit_velocity_) 1 MPI processes</div><div> type: seqaij</div><div> rows=962, cols=962</div><div> total: nonzeros=19908, allocated nonzeros=19908</div><div> total number of mallocs used during MatSetValues calls =0</div><div> using I-node routines: found 481 nodes, limit used is 5</div><div> KSP solver for S = A11 - A10 inv(A00) A01 </div><div> KSP Object: (fieldsplit_pressure_) 1 MPI processes</div><div> type: gmres</div><div> GMRES: restart=30, using Classical (unmodified) Gram-Schmidt Orthogonalization with no iterative refinement</div><div> GMRES: happy breakdown tolerance 1e-30</div><div> maximum iterations=10000, initial guess is zero</div><div> tolerances: relative=1e-10, absolute=1e-50, divergence=10000</div><div> left preconditioning</div><div> using PRECONDITIONED norm type for convergence test</div><div> PC Object: (fieldsplit_pressure_) 1 MPI processes</div><div> type: jacobi</div><div> linear system matrix followed by preconditioner matrix:</div><div> Mat Object: (fieldsplit_pressure_) 1 MPI processes</div><div> type: schurcomplement</div><div> rows=145, cols=145</div><div> has attached null space</div><div> Schur complement A11 - A10 inv(A00) A01</div><div> A11</div><div> Mat Object: (fieldsplit_pressure_) 1 MPI processes</div><div> type: seqaij</div><div> rows=145, cols=145</div><div> total: nonzeros=945, allocated nonzeros=945</div><div> total number of mallocs used during MatSetValues calls =0</div><div> has attached null space</div><div> not using I-node routines</div><div> A10</div><div> Mat Object: 1 MPI processes</div><div> type: seqaij</div><div> rows=145, cols=962</div><div> total: nonzeros=4466, allocated nonzeros=4466</div><div> total number of mallocs used during MatSetValues calls =0</div><div> not using I-node routines</div><div> KSP of A00</div><div> KSP Object: (fieldsplit_pressure_inner_) 1 MPI processes</div><div> type: preonly</div><div> maximum iterations=10000, initial guess is zero</div><div> tolerances: relative=1e-09, absolute=1e-50, divergence=10000</div><div> left preconditioning</div><div> using NONE norm type for convergence test</div><div> PC Object: (fieldsplit_pressure_inner_) 1 MPI processes</div><div> type: jacobi</div><div> linear system matrix = precond matrix:</div><div> Mat Object: (fieldsplit_velocity_) 1 MPI processes</div><div> type: seqaij</div><div> rows=962, cols=962</div><div> total: nonzeros=19908, allocated nonzeros=19908</div><div> total number of mallocs used during MatSetValues calls =0</div><div> using I-node routines: found 481 nodes, limit used is 5</div><div> A01</div><div> Mat Object: 1 MPI processes</div><div> type: seqaij</div><div> rows=962, cols=145</div><div> total: nonzeros=4466, allocated nonzeros=4466</div><div> total number of mallocs used during MatSetValues calls =0</div><div> using I-node routines: found 481 nodes, limit used is 5</div><div> Mat Object: 1 MPI processes</div><div> type: seqaij</div><div> rows=145, cols=145</div><div> total: nonzeros=2601, allocated nonzeros=2601</div><div> total number of mallocs used during MatSetValues calls =0</div><div> not using I-node routines</div><div> linear system matrix = precond matrix:</div><div> Mat Object: 1 MPI processes</div><div> type: seqaij</div><div> rows=1107, cols=1107</div><div> total: nonzeros=29785, allocated nonzeros=29785</div><div> total number of mallocs used during MatSetValues calls =0</div><div> has attached null space</div><div> using I-node routines: found 513 nodes, limit used is 5</div></div><div><br></div><div> Thanks,</div><div><br></div><div> Matt</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div dir="ltr"><div name="divtagdefaultwrapper" style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0);margin:0px">
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<div dir="ltr"><font style="font-size:11pt" color="#000000" face="Calibri, sans-serif"><b>From:</b> Matthew Knepley <<a href="mailto:knepley@gmail.com" target="_blank">knepley@gmail.com</a>><br>
<b>Sent:</b> Friday, September 05, 2014 12:36 AM<br>
<b>To:</b> Klaij, Christiaan<br>
<b>Cc:</b> <a href="mailto:petsc-users@mcs.anl.gov" target="_blank">petsc-users@mcs.anl.gov</a><br>
<b>Subject:</b> Re: [petsc-users] fieldsplit_0_ monitor in combination with selfp</font>
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<div class="gmail_quote">On Thu, Sep 4, 2014 at 7:26 AM, Klaij, Christiaan <span dir="ltr">
<<a href="mailto:C.Klaij@marin.nl" target="_blank">C.Klaij@marin.nl</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
Sorry, here's the ksp_view. I'm expecting<br>
<br>
-fieldsplit_1_inner_ksp_type preonly<br>
<br>
to set the ksp(A00) in the Schur complement only, but it seems to set it in the inv(A00) of the diagonal as well.<br>
</blockquote>
<div><br>
</div>
<div>I think something is wrong in your example (we strongly advise against using MatNest directly). I cannot reproduce this using SNES ex62:</div>
<div><br>
</div>
<div> ./config/builder2.py check src/snes/examples/tutorials/ex62.c --testnum=36 --args="-fieldsplit_pressure_inner_ksp_type preonly -fieldsplit_pressure_inner_pc_type jacobi"</div>
<div><br>
</div>
<div>which translates to</div>
<div><br>
</div>
<div> ex62 -run_type full -refinement_limit 0.00625 -bc_type dirichlet -interpolate 1 -vel_petscspace_order 2 -pres_petscspace_order 1 -ksp_type fgmres -ksp_gmres_restart 100 -ksp_rtol 1.0e-9 -pc_type fieldsplit -pc_fieldsplit_type schur -pc_fieldsplit_schur_factorization_type
full -fieldsplit_pressure_ksp_rtol 1e-10 -fieldsplit_velocity_ksp_type gmres -fieldsplit_velocity_pc_type lu -fieldsplit_pressure_pc_type jacobi -snes_monitor_short -ksp_monitor_short -snes_converged_reason -ksp_converged_reason -snes_view -show_solution 0
-fieldsplit_pressure_inner_ksp_type preonly -fieldsplit_pressure_inner_pc_type jacobi</div>
<div><br>
</div>
<div>gives</div>
<div><br>
</div>
<div> Nonlinear solve converged due to CONVERGED_FNORM_RELATIVE iterations 1</div>
<div>SNES Object: 1 MPI processes</div>
<div> type: newtonls</div>
<div> maximum iterations=50, maximum function evaluations=10000</div>
<div> tolerances: relative=1e-08, absolute=1e-50, solution=1e-08</div>
<div> total number of linear solver iterations=20</div>
<div> total number of function evaluations=2</div>
<div> SNESLineSearch Object: 1 MPI processes</div>
<div> type: bt</div>
<div> interpolation: cubic</div>
<div> alpha=1.000000e-04</div>
<div> maxstep=1.000000e+08, minlambda=1.000000e-12</div>
<div> tolerances: relative=1.000000e-08, absolute=1.000000e-15, lambda=1.000000e-08</div>
<div> maximum iterations=40</div>
<div> KSP Object: 1 MPI processes</div>
<div> type: fgmres</div>
<div> GMRES: restart=100, using Classical (unmodified) Gram-Schmidt Orthogonalization with no iterative refinement</div>
<div> GMRES: happy breakdown tolerance 1e-30</div>
<div> maximum iterations=10000, initial guess is zero</div>
<div> tolerances: relative=1e-09, absolute=1e-50, divergence=10000</div>
<div> right preconditioning</div>
<div> has attached null space</div>
<div> using UNPRECONDITIONED norm type for convergence test</div>
<div> PC Object: 1 MPI processes</div>
<div> type: fieldsplit</div>
<div> FieldSplit with Schur preconditioner, factorization FULL</div>
<div> Preconditioner for the Schur complement formed from A11</div>
<div> Split info:</div>
<div> Split number 0 Defined by IS</div>
<div> Split number 1 Defined by IS</div>
<div> KSP solver for A00 block</div>
<div> KSP Object: (fieldsplit_velocity_) 1 MPI processes</div>
<div> type: gmres</div>
<div> GMRES: restart=30, using Classical (unmodified) Gram-Schmidt Orthogonalization with no iterative refinement</div>
<div> GMRES: happy breakdown tolerance 1e-30</div>
<div> maximum iterations=10000, initial guess is zero</div>
<div> tolerances: relative=1e-05, absolute=1e-50, divergence=10000</div>
<div> left preconditioning</div>
<div> using PRECONDITIONED norm type for convergence test</div>
<div> PC Object: (fieldsplit_velocity_) 1 MPI processes</div>
<div> type: lu</div>
<div> LU: out-of-place factorization</div>
<div> tolerance for zero pivot 2.22045e-14</div>
<div> matrix ordering: nd</div>
<div> factor fill ratio given 5, needed 3.45047</div>
<div> Factored matrix follows:</div>
<div> Mat Object: 1 MPI processes</div>
<div> type: seqaij</div>
<div> rows=962, cols=962</div>
<div> package used to perform factorization: petsc</div>
<div> total: nonzeros=68692, allocated nonzeros=68692</div>
<div> total number of mallocs used during MatSetValues calls =0</div>
<div> using I-node routines: found 456 nodes, limit used is 5</div>
<div> linear system matrix = precond matrix:</div>
<div> Mat Object: (fieldsplit_velocity_) 1 MPI processes</div>
<div> type: seqaij</div>
<div> rows=962, cols=962</div>
<div> total: nonzeros=19908, allocated nonzeros=19908</div>
<div> total number of mallocs used during MatSetValues calls =0</div>
<div> using I-node routines: found 481 nodes, limit used is 5</div>
<div> KSP solver for S = A11 - A10 inv(A00) A01 </div>
<div> KSP Object: (fieldsplit_pressure_) 1 MPI processes</div>
<div> type: gmres</div>
<div> GMRES: restart=30, using Classical (unmodified) Gram-Schmidt Orthogonalization with no iterative refinement</div>
<div> GMRES: happy breakdown tolerance 1e-30</div>
<div> maximum iterations=10000, initial guess is zero</div>
<div> tolerances: relative=1e-10, absolute=1e-50, divergence=10000</div>
<div> left preconditioning</div>
<div> has attached null space</div>
<div> using PRECONDITIONED norm type for convergence test</div>
<div> PC Object: (fieldsplit_pressure_) 1 MPI processes</div>
<div> type: jacobi</div>
<div> linear system matrix followed by preconditioner matrix:</div>
<div> Mat Object: (fieldsplit_pressure_) 1 MPI processes</div>
<div> type: schurcomplement</div>
<div> rows=145, cols=145</div>
<div> has attached null space</div>
<div> Schur complement A11 - A10 inv(A00) A01</div>
<div> A11</div>
<div> Mat Object: (fieldsplit_pressure_) 1 MPI processes</div>
<div> type: seqaij</div>
<div> rows=145, cols=145</div>
<div> total: nonzeros=945, allocated nonzeros=945</div>
<div> total number of mallocs used during MatSetValues calls =0</div>
<div> has attached null space</div>
<div> not using I-node routines</div>
<div> A10</div>
<div> Mat Object: 1 MPI processes</div>
<div> type: seqaij</div>
<div> rows=145, cols=962</div>
<div> total: nonzeros=4466, allocated nonzeros=4466</div>
<div> total number of mallocs used during MatSetValues calls =0</div>
<div> not using I-node routines</div>
<div> KSP of A00</div>
<div> KSP Object: (fieldsplit_pressure_inner_) 1 MPI processes</div>
<div> type: preonly</div>
<div> maximum iterations=10000, initial guess is zero</div>
<div> tolerances: relative=1e-09, absolute=1e-50, divergence=10000</div>
<div> left preconditioning</div>
<div> using NONE norm type for convergence test</div>
<div> PC Object: (fieldsplit_pressure_inner_) 1 MPI processes</div>
<div> type: jacobi</div>
<div> linear system matrix = precond matrix:</div>
<div> Mat Object: (fieldsplit_velocity_) 1 MPI processes</div>
<div> type: seqaij</div>
<div> rows=962, cols=962</div>
<div> total: nonzeros=19908, allocated nonzeros=19908</div>
<div> total number of mallocs used during MatSetValues calls =0</div>
<div> using I-node routines: found 481 nodes, limit used is 5</div>
<div> A01</div>
<div> Mat Object: 1 MPI processes</div>
<div> type: seqaij</div>
<div> rows=962, cols=145</div>
<div> total: nonzeros=4466, allocated nonzeros=4466</div>
<div> total number of mallocs used during MatSetValues calls =0</div>
<div> using I-node routines: found 481 nodes, limit used is 5</div>
<div> Mat Object: (fieldsplit_pressure_) 1 MPI processes</div>
<div> type: seqaij</div>
<div> rows=145, cols=145</div>
<div> total: nonzeros=945, allocated nonzeros=945</div>
<div> total number of mallocs used during MatSetValues calls =0</div>
<div> has attached null space</div>
<div> not using I-node routines</div>
<div> linear system matrix = precond matrix:</div>
<div> Mat Object: 1 MPI processes</div>
<div> type: seqaij</div>
<div> rows=1107, cols=1107</div>
<div> total: nonzeros=29785, allocated nonzeros=29785</div>
<div> total number of mallocs used during MatSetValues calls =0</div>
<div> has attached null space</div>
<div> using I-node routines: found 513 nodes, limit used is 5</div>
<div><br>
</div>
<div> Matt</div>
<div> </div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
Chris<br>
<br>
0 KSP Residual norm 1.229687498638e+00<br>
Residual norms for fieldsplit_1_ solve.<br>
0 KSP Residual norm 7.185799114488e+01<br>
1 KSP Residual norm 3.873274154012e+01<br>
1 KSP Residual norm 1.107969383366e+00<br>
KSP Object: 1 MPI processes<br>
type: fgmres<br>
GMRES: restart=30, using Classical (unmodified) Gram-Schmidt Orthogonalization with no iterative refinement<br>
GMRES: happy breakdown tolerance 1e-30<br>
maximum iterations=1, initial guess is zero<br>
tolerances: relative=1e-05, absolute=1e-50, divergence=10000<br>
right preconditioning<br>
using UNPRECONDITIONED norm type for convergence test<br>
PC Object: 1 MPI processes<br>
type: fieldsplit<br>
FieldSplit with Schur preconditioner, factorization LOWER<br>
Preconditioner for the Schur complement formed from Sp, an assembled approximation to S, which uses (the lumped) A00's diagonal's inverse<br>
Split info:<br>
Split number 0 Defined by IS<br>
Split number 1 Defined by IS<br>
KSP solver for A00 block<br>
KSP Object: (fieldsplit_0_) 1 MPI processes<br>
type: preonly<br>
maximum iterations=1, initial guess is zero<br>
tolerances: relative=1e-05, absolute=1e-50, divergence=10000<br>
left preconditioning<br>
using NONE norm type for convergence test<br>
PC Object: (fieldsplit_0_) 1 MPI processes<br>
type: bjacobi<br>
block Jacobi: number of blocks = 1<br>
Local solve is same for all blocks, in the following KSP and PC objects:<br>
KSP Object: (fieldsplit_0_sub_) 1 MPI processes<br>
type: preonly<br>
maximum iterations=10000, initial guess is zero<br>
tolerances: relative=1e-05, absolute=1e-50, divergence=10000<br>
left preconditioning<br>
using NONE norm type for convergence test<br>
PC Object: (fieldsplit_0_sub_) 1 MPI processes<br>
type: ilu<br>
ILU: out-of-place factorization<br>
0 levels of fill<br>
tolerance for zero pivot 2.22045e-14<br>
using diagonal shift on blocks to prevent zero pivot [INBLOCKS]<br>
matrix ordering: natural<br>
factor fill ratio given 1, needed 1<br>
Factored matrix follows:<br>
Mat Object: 1 MPI processes<br>
type: seqaij<br>
rows=48, cols=48<br>
package used to perform factorization: petsc<br>
total: nonzeros=200, allocated nonzeros=200<br>
total number of mallocs used during MatSetValues calls =0<br>
not using I-node routines<br>
linear system matrix = precond matrix:<br>
Mat Object: (fieldsplit_0_) 1 MPI processes<br>
type: seqaij<br>
rows=48, cols=48<br>
total: nonzeros=200, allocated nonzeros=240<br>
total number of mallocs used during MatSetValues calls =0<br>
not using I-node routines<br>
linear system matrix = precond matrix:<br>
Mat Object: (fieldsplit_0_) 1 MPI processes<br>
type: mpiaij<br>
rows=48, cols=48<br>
total: nonzeros=200, allocated nonzeros=480<br>
total number of mallocs used during MatSetValues calls =0<br>
not using I-node (on process 0) routines<br>
KSP solver for S = A11 - A10 inv(A00) A01<br>
KSP Object: (fieldsplit_1_) 1 MPI processes<br>
type: gmres<br>
GMRES: restart=30, using Classical (unmodified) Gram-Schmidt Orthogonalization with no iterative refinement<br>
GMRES: happy breakdown tolerance 1e-30<br>
maximum iterations=1, initial guess is zero<br>
tolerances: relative=1e-05, absolute=1e-50, divergence=10000<br>
left preconditioning<br>
using PRECONDITIONED norm type for convergence test<br>
PC Object: (fieldsplit_1_) 1 MPI processes<br>
type: bjacobi<br>
block Jacobi: number of blocks = 1<br>
Local solve is same for all blocks, in the following KSP and PC objects:<br>
KSP Object: (fieldsplit_1_sub_) 1 MPI processes<br>
type: preonly<br>
maximum iterations=10000, initial guess is zero<br>
tolerances: relative=1e-05, absolute=1e-50, divergence=10000<br>
left preconditioning<br>
using NONE norm type for convergence test<br>
PC Object: (fieldsplit_1_sub_) 1 MPI processes<br>
type: bjacobi<br>
block Jacobi: number of blocks = 1<br>
Local solve is same for all blocks, in the following KSP and PC objects:<br>
KSP Object: (fieldsplit_1_sub_sub_) 1 MPI processes<br>
type: preonly<br>
maximum iterations=10000, initial guess is zero<br>
tolerances: relative=1e-05, absolute=1e-50, divergence=10000<br>
left preconditioning<br>
using NONE norm type for convergence test<br>
PC Object: (fieldsplit_1_sub_sub_) 1 MPI processes<br>
type: ilu<br>
ILU: out-of-place factorization<br>
0 levels of fill<br>
tolerance for zero pivot 2.22045e-14<br>
using diagonal shift on blocks to prevent zero pivot [INBLOCKS]<br>
matrix ordering: natural<br>
factor fill ratio given 1, needed 1<br>
Factored matrix follows:<br>
Mat Object: 1 MPI processes<br>
type: seqaij<br>
rows=24, cols=24<br>
package used to perform factorization: petsc<br>
total: nonzeros=120, allocated nonzeros=120<br>
total number of mallocs used during MatSetValues calls =0<br>
not using I-node routines<br>
linear system matrix = precond matrix:<br>
Mat Object: 1 MPI processes<br>
type: seqaij<br>
rows=24, cols=24<br>
total: nonzeros=120, allocated nonzeros=120<br>
total number of mallocs used during MatSetValues calls =0<br>
not using I-node routines<br>
linear system matrix = precond matrix:<br>
Mat Object: 1 MPI processes<br>
type: mpiaij<br>
rows=24, cols=24<br>
total: nonzeros=120, allocated nonzeros=120<br>
total number of mallocs used during MatSetValues calls =0<br>
not using I-node (on process 0) routines<br>
linear system matrix followed by preconditioner matrix:<br>
Mat Object: (fieldsplit_1_) 1 MPI processes<br>
type: schurcomplement<br>
rows=24, cols=24<br>
Schur complement A11 - A10 inv(A00) A01<br>
A11<br>
Mat Object: (fieldsplit_1_) 1 MPI processes<br>
type: mpiaij<br>
rows=24, cols=24<br>
total: nonzeros=0, allocated nonzeros=0<br>
total number of mallocs used during MatSetValues calls =0<br>
using I-node (on process 0) routines: found 5 nodes, limit used is 5<br>
A10<br>
Mat Object: (a10_) 1 MPI processes<br>
type: mpiaij<br>
rows=24, cols=48<br>
total: nonzeros=96, allocated nonzeros=96<br>
total number of mallocs used during MatSetValues calls =0<br>
not using I-node (on process 0) routines<br>
KSP of A00<br>
KSP Object: (fieldsplit_1_inner_) 1 MPI processes<br>
type: preonly<br>
maximum iterations=1, initial guess is zero<br>
tolerances: relative=1e-05, absolute=1e-50, divergence=10000<br>
left preconditioning<br>
using NONE norm type for convergence test<br>
PC Object: (fieldsplit_1_inner_) 1 MPI processes<br>
type: jacobi<br>
linear system matrix = precond matrix:<br>
Mat Object: (fieldsplit_0_) 1 MPI processes<br>
type: mpiaij<br>
rows=48, cols=48<br>
total: nonzeros=200, allocated nonzeros=480<br>
total number of mallocs used during MatSetValues calls =0<br>
not using I-node (on process 0) routines<br>
A01<br>
Mat Object: (a01_) 1 MPI processes<br>
type: mpiaij<br>
rows=48, cols=24<br>
total: nonzeros=96, allocated nonzeros=480<br>
total number of mallocs used during MatSetValues calls =0<br>
not using I-node (on process 0) routines<br>
Mat Object: 1 MPI processes<br>
type: mpiaij<br>
rows=24, cols=24<br>
total: nonzeros=120, allocated nonzeros=120<br>
total number of mallocs used during MatSetValues calls =0<br>
not using I-node (on process 0) routines<br>
linear system matrix = precond matrix:<br>
Mat Object: 1 MPI processes<br>
type: nest<br>
rows=72, cols=72<br>
Matrix object:<br>
type=nest, rows=2, cols=2<br>
MatNest structure:<br>
(0,0) : prefix="fieldsplit_0_", type=mpiaij, rows=48, cols=48<br>
(0,1) : prefix="a01_", type=mpiaij, rows=48, cols=24<br>
(1,0) : prefix="a10_", type=mpiaij, rows=24, cols=48<br>
(1,1) : prefix="fieldsplit_1_", type=mpiaij, rows=24, cols=24<br>
<br>
<br>
From: Matthew Knepley <<a href="mailto:knepley@gmail.com" target="_blank">knepley@gmail.com</a>><br>
Sent: Thursday, September 04, 2014 2:20 PM<br>
To: Klaij, Christiaan<br>
Cc: <a href="mailto:petsc-users@mcs.anl.gov" target="_blank">petsc-users@mcs.anl.gov</a><br>
Subject: Re: [petsc-users] fieldsplit_0_ monitor in combination with selfp<br>
<br>
<br>
<br>
<br>
On Thu, Sep 4, 2014 at 7:06 AM, Klaij, Christiaan <<a href="mailto:C.Klaij@marin.nl" target="_blank">C.Klaij@marin.nl</a>> wrote:<br>
I'm playing with the selfp option in fieldsplit using<br>
snes/examples/tutorials/ex70.c. For example:<br>
<br>
mpiexec -n 2 ./ex70 -nx 4 -ny 6 \<br>
-ksp_type fgmres \<br>
-pc_type fieldsplit \<br>
-pc_fieldsplit_type schur \<br>
-pc_fieldsplit_schur_fact_type lower \<br>
-pc_fieldsplit_schur_precondition selfp \<br>
-fieldsplit_1_inner_ksp_type preonly \<br>
-fieldsplit_1_inner_pc_type jacobi \<br>
-fieldsplit_0_ksp_monitor -fieldsplit_0_ksp_max_it 1 \<br>
-fieldsplit_1_ksp_monitor -fieldsplit_1_ksp_max_it 1 \<br>
-ksp_monitor -ksp_max_it 1<br>
<br>
gives the following output<br>
<br>
0 KSP Residual norm 1.229687498638e+00<br>
Residual norms for fieldsplit_1_ solve.<br>
0 KSP Residual norm 2.330138480101e+01<br>
1 KSP Residual norm 1.609000846751e+01<br>
1 KSP Residual norm 1.180287268335e+00<br>
<br>
To my suprise I don't see anything for the fieldsplit_0_ solve,<br>
why?<br>
<br>
<br>
<br>
Always run with -ksp_view for any solver question.<br>
<br>
<br>
Thanks,<br>
<br>
<br>
Matt<br>
Furthermore, if I understand correctly the above should be<br>
exactly equivalent with<br>
<br>
mpiexec -n 2 ./ex70 -nx 4 -ny 6 \<br>
-ksp_type fgmres \<br>
-pc_type fieldsplit \<br>
-pc_fieldsplit_type schur \<br>
-pc_fieldsplit_schur_fact_type lower \<br>
-user_ksp \<br>
-fieldsplit_0_ksp_monitor -fieldsplit_0_ksp_max_it 1 \<br>
-fieldsplit_1_ksp_monitor -fieldsplit_1_ksp_max_it 1 \<br>
-ksp_monitor -ksp_max_it 1<br>
<br>
0 KSP Residual norm 1.229687498638e+00<br>
Residual norms for fieldsplit_0_ solve.<br>
0 KSP Residual norm 5.486639587672e-01<br>
1 KSP Residual norm 6.348354253703e-02<br>
Residual norms for fieldsplit_1_ solve.<br>
0 KSP Residual norm 2.321938107977e+01<br>
1 KSP Residual norm 1.605484031258e+01<br>
1 KSP Residual norm 1.183225251166e+00<br>
<br>
because -user_ksp replaces the Schur complement by the simple<br>
approximation A11 - A10 inv(diag(A00)) A01. Beside the missing<br>
fielsplit_0_ part, the numbers are pretty close but not exactly<br>
the same. Any explanation?<br>
<br>
Chris<br>
<br>
<br>
dr. ir. Christiaan Klaij<br>
CFD Researcher<br>
Research & Development<br>
E mailto:<a href="mailto:C.Klaij@marin.nl" target="_blank">C.Klaij@marin.nl</a><br>
T <a href="tel:%2B31%20317%2049%2033%2044" value="+31317493344" target="_blank">+31 317 49 33 44</a><br>
<br>
<br>
MARIN<br>
2, Haagsteeg, P.O. Box 28, 6700 AA Wageningen, The Netherlands<br>
T <a href="tel:%2B31%20317%2049%2039%2011" value="+31317493911" target="_blank">+31 317 49 39 11</a>, F
<a href="tel:%2B31%20317%2049%2032%2045" value="+31317493245" target="_blank">+31 317 49 32 45</a>, I
<a href="http://www.marin.nl" target="_blank">www.marin.nl</a><br>
<br>
<br>
<br>
<br>
<br>
--<br>
What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.<br>
-- Norbert Wiener </blockquote><span><font color="#888888">
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-- <br>
What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.<br>
-- Norbert Wiener </font></span></div>
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</blockquote></div><br><br clear="all"><div><br></div>-- <br>What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.<br>-- Norbert Wiener
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