Yes, the original operator definitely has a constant null space corresponding to the constant pressure mode. I am currently handling this by using the MatSetNullSpace function when the matrix is being created. Does this information get passed to the submatrices of the fieldsplit?
-Colton On Thu, May 23, 2024 at 12:36 PM Barry Smith <[email protected]> wrote: > > Ok, > > So what is happening is that GMRES with a restart of 30 is running on > the Schur complement system with no preconditioning and LU (as a direct > solver) is being used in the application of S (the Schur complement). The > convergence of GMRES is stagnating after getting about 8 digits of accuracy > in the residual. Then at the second GMRES > restart it is comparing the explicitly computing residual b - Ax with that > computed inside the GMRES algorithm (via a recursive formula) and finding a > large difference so generating an error. Since you are using a direct > solver on the A_{00} block and it is well-conditioned this problem is not > expected. > > Is it possible that the S operator has a null space (perhaps of the > constant vector)? Or, relatedly, does your original full matrix have a null > space? > > We have a way to associated null spaces of the submatrices in > PCFIELDSPLIT by attaching them to the IS that define the fields, but > unfortunately not trivially when using -pc_fieldsplit_detect_saddle_point. > And sadly the current support seems completely undocumented. > > Barry > > > > On May 23, 2024, at 2:16 PM, Colton Bryant < > [email protected]> wrote: > > Hi Barry, > > I saw that was reporting as an unused option and the error message I sent > was run with -fieldsplit_0_ksp_type preonly. > > -Colton > > On Thu, May 23, 2024 at 12:13 PM Barry Smith <[email protected]> wrote: > >> >> >> Sorry I gave the wrong option. Use -fieldsplit_0_ksp_type preonly >> >> Barry >> >> On May 23, 2024, at 12:51 PM, Colton Bryant < >> [email protected]> wrote: >> >> That produces the error: >> >> [0]PETSC ERROR: Residual norm computed by GMRES recursion formula >> 2.68054e-07 is far from the computed residual norm 6.86309e-06 at restart, >> residual norm at start of cycle 2.68804e-07 >> >> The rest of the error is identical. >> >> On Thu, May 23, 2024 at 10:46 AM Barry Smith <[email protected]> wrote: >> >>> >>> Use -pc_fieldsplit_0_ksp_type preonly >>> >>> >>> >>> On May 23, 2024, at 12:43 PM, Colton Bryant < >>> [email protected]> wrote: >>> >>> That produces the following error: >>> >>> [0]PETSC ERROR: Residual norm computed by GMRES recursion formula >>> 2.79175e-07 is far from the computed residual norm 0.000113154 at restart, >>> residual norm at start of cycle 2.83065e-07 >>> [0]PETSC ERROR: See >>> https://urldefense.us/v3/__https://petsc.org/release/faq/__;!!G_uCfscf7eWS!aHWJfYufqSwgiA17iAHR0cE5dtx0vFkWJgFdirxQmSy__IYOi9ZtKDa3Qu9Ikh-Yj15tnuGl678edZxCaWoiSHFkTcL1O5l1oWPACScr9kM$ >>> for trouble shooting. >>> [0]PETSC ERROR: Petsc Release Version 3.21.0, unknown >>> [0]PETSC ERROR: ./mainOversetLS_exe on a arch-linux-c-opt named glass by >>> colton Thu May 23 10:41:09 2024 >>> [0]PETSC ERROR: Configure options --download-mpich --with-cc=gcc >>> --with-cxx=g++ --with-debugging=no --with-fc=gfortran COPTFLAGS=-O3 >>> CXXOPTFLAGS=-O3 FOPTFLAGS=-O3 PETSC_ARCH=arch-linux-c-opt --download-sowing >>> [0]PETSC ERROR: #1 KSPGMRESCycle() at >>> /home/colton/petsc/src/ksp/ksp/impls/gmres/gmres.c:115 >>> [0]PETSC ERROR: #2 KSPSolve_GMRES() at >>> /home/colton/petsc/src/ksp/ksp/impls/gmres/gmres.c:227 >>> [0]PETSC ERROR: #3 KSPSolve_Private() at >>> /home/colton/petsc/src/ksp/ksp/interface/itfunc.c:905 >>> [0]PETSC ERROR: #4 KSPSolve() at >>> /home/colton/petsc/src/ksp/ksp/interface/itfunc.c:1078 >>> [0]PETSC ERROR: #5 PCApply_FieldSplit_Schur() at >>> /home/colton/petsc/src/ksp/pc/impls/fieldsplit/fieldsplit.c:1203 >>> [0]PETSC ERROR: #6 PCApply() at >>> /home/colton/petsc/src/ksp/pc/interface/precon.c:497 >>> [0]PETSC ERROR: #7 KSP_PCApply() at >>> /home/colton/petsc/include/petsc/private/kspimpl.h:409 >>> [0]PETSC ERROR: #8 KSPFGMRESCycle() at >>> /home/colton/petsc/src/ksp/ksp/impls/gmres/fgmres/fgmres.c:123 >>> [0]PETSC ERROR: #9 KSPSolve_FGMRES() at >>> /home/colton/petsc/src/ksp/ksp/impls/gmres/fgmres/fgmres.c:235 >>> [0]PETSC ERROR: #10 KSPSolve_Private() at >>> /home/colton/petsc/src/ksp/ksp/interface/itfunc.c:905 >>> [0]PETSC ERROR: #11 KSPSolve() at >>> /home/colton/petsc/src/ksp/ksp/interface/itfunc.c:1078 >>> [0]PETSC ERROR: #12 solveStokes() at cartesianStokesGrid.cpp:1403 >>> >>> >>> >>> On Thu, May 23, 2024 at 10:33 AM Barry Smith <[email protected]> wrote: >>> >>>> >>>> Run the failing case with also -ksp_error_if_not_converged so we see >>>> exactly where the problem is first detected. >>>> >>>> >>>> >>>> >>>> On May 23, 2024, at 11:51 AM, Colton Bryant < >>>> [email protected]> wrote: >>>> >>>> Hi Barry, >>>> >>>> Thanks for letting me know about the need to use fgmres in this case. I >>>> ran a smaller problem (1230 in the first block) and saw similar behavior in >>>> the true residual. >>>> >>>> I also ran the same problem with the options -fieldsplit_0_pc_type svd >>>> -fieldsplit_0_pc_svd_monitor and get the following output: >>>> SVD: condition number 1.933639985881e+03, 0 of 1230 singular >>>> values are (nearly) zero >>>> SVD: smallest singular values: 4.132036392141e-03 >>>> 4.166444542385e-03 4.669534028645e-03 4.845532162256e-03 5.047038625390e-03 >>>> SVD: largest singular values : 7.947990616611e+00 >>>> 7.961437414477e+00 7.961851612473e+00 7.971335373142e+00 7.989870790960e+00 >>>> >>>> I would be surprised if the A_{00} block is ill conditioned as it's >>>> just a standard discretization of the laplacian with some rows replaced >>>> with ones on the diagonal due to interpolations from the overset mesh. I'm >>>> wondering if I'm somehow violating a solvability condition of the problem? >>>> >>>> Thanks for the help! >>>> >>>> -Colton >>>> >>>> On Wed, May 22, 2024 at 6:09 PM Barry Smith <[email protected]> wrote: >>>> >>>>> >>>>> Thanks for the info. I see you are using GMRES inside the Schur >>>>> complement solver, this is ok but when you do you need to use fgmres as >>>>> the >>>>> outer solver. But this is unlikely to be the cause of the exact problem >>>>> you >>>>> are seeing. >>>>> >>>>> I'm not sure why the Schur complement KSP is suddenly seeing a large >>>>> increase in the true residual norm. Is it possible the A_{00} block is >>>>> ill-conditioned? >>>>> >>>>> Can you run with a smaller problem? Say 2,000 or so in the first >>>>> block? Is there still a problem? >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> On May 22, 2024, at 6:00 PM, Colton Bryant < >>>>> [email protected]> wrote: >>>>> >>>>> Hi Barry, >>>>> >>>>> I have not used any other solver parameters in the code and the full >>>>> set of solver related command line options are those I mentioned in the >>>>> previous email. >>>>> >>>>> Below is the output from -ksp_view: >>>>> >>>>> KSP Object: (back_) 1 MPI process >>>>> type: gmres >>>>> restart=30, using Classical (unmodified) Gram-Schmidt >>>>> Orthogonalization with no iterative refinement >>>>> happy breakdown tolerance 1e-30 >>>>> maximum iterations=10000, initial guess is zero >>>>> tolerances: relative=1e-08, absolute=1e-50, divergence=10000. >>>>> left preconditioning >>>>> using PRECONDITIONED norm type for convergence test >>>>> PC Object: (back_) 1 MPI process >>>>> type: fieldsplit >>>>> FieldSplit with Schur preconditioner, blocksize = 1, factorization >>>>> FULL >>>>> Preconditioner for the Schur complement formed from S itself >>>>> Split info: >>>>> Split number 0 Defined by IS >>>>> Split number 1 Defined by IS >>>>> KSP solver for A00 block >>>>> KSP Object: (back_fieldsplit_0_) 1 MPI process >>>>> type: gmres >>>>> restart=30, using Classical (unmodified) Gram-Schmidt >>>>> Orthogonalization with no iterative refinement >>>>> happy breakdown tolerance 1e-30 >>>>> maximum iterations=10000, initial guess is zero >>>>> tolerances: relative=1e-05, absolute=1e-50, divergence=10000. >>>>> left preconditioning >>>>> using PRECONDITIONED norm type for convergence test >>>>> PC Object: (back_fieldsplit_0_) 1 MPI process >>>>> type: lu >>>>> out-of-place factorization >>>>> tolerance for zero pivot 2.22045e-14 >>>>> matrix ordering: nd >>>>> factor fill ratio given 5., needed 8.83482 >>>>> Factored matrix follows: >>>>> Mat Object: (back_fieldsplit_0_) 1 MPI process >>>>> type: seqaij >>>>> rows=30150, cols=30150 >>>>> package used to perform factorization: petsc >>>>> total: nonzeros=2649120, allocated nonzeros=2649120 >>>>> using I-node routines: found 15019 nodes, limit used >>>>> is 5 >>>>> linear system matrix = precond matrix: >>>>> Mat Object: (back_fieldsplit_0_) 1 MPI process >>>>> type: seqaij >>>>> rows=30150, cols=30150 >>>>> total: nonzeros=299850, allocated nonzeros=299850 >>>>> total number of mallocs used during MatSetValues calls=0 >>>>> using I-node routines: found 15150 nodes, limit used is 5 >>>>> KSP solver for S = A11 - A10 inv(A00) A01 >>>>> KSP Object: (back_fieldsplit_1_) 1 MPI process >>>>> type: gmres >>>>> restart=30, using Classical (unmodified) Gram-Schmidt >>>>> Orthogonalization with no iterative refinement >>>>> happy breakdown tolerance 1e-30 >>>>> maximum iterations=10000, initial guess is zero >>>>> tolerances: relative=1e-08, absolute=1e-50, divergence=10000. >>>>> left preconditioning >>>>> using PRECONDITIONED norm type for convergence test >>>>> PC Object: (back_fieldsplit_1_) 1 MPI process >>>>> type: none >>>>> linear system matrix = precond matrix: >>>>> Mat Object: (back_fieldsplit_1_) 1 MPI process >>>>> type: schurcomplement >>>>> rows=15000, cols=15000 >>>>> Schur complement A11 - A10 inv(A00) A01 >>>>> A11 >>>>> Mat Object: (back_fieldsplit_1_) 1 MPI process >>>>> type: seqaij >>>>> rows=15000, cols=15000 >>>>> total: nonzeros=74700, allocated nonzeros=74700 >>>>> total number of mallocs used during MatSetValues >>>>> calls=0 >>>>> not using I-node routines >>>>> A10 >>>>> Mat Object: 1 MPI process >>>>> type: seqaij >>>>> rows=15000, cols=30150 >>>>> total: nonzeros=149550, allocated nonzeros=149550 >>>>> total number of mallocs used during MatSetValues >>>>> calls=0 >>>>> not using I-node routines >>>>> KSP solver for A00 block viewable with the additional >>>>> option -back_fieldsplit_0_ksp_view >>>>> A01 >>>>> Mat Object: 1 MPI process >>>>> type: seqaij >>>>> rows=30150, cols=15000 >>>>> total: nonzeros=149550, allocated nonzeros=149550 >>>>> total number of mallocs used during MatSetValues >>>>> calls=0 >>>>> using I-node routines: found 15150 nodes, limit used >>>>> is 5 >>>>> linear system matrix = precond matrix: >>>>> Mat Object: (back_) 1 MPI process >>>>> type: seqaij >>>>> rows=45150, cols=45150 >>>>> total: nonzeros=673650, allocated nonzeros=673650 >>>>> total number of mallocs used during MatSetValues calls=0 >>>>> has attached null space >>>>> using I-node routines: found 15150 nodes, limit used is 5 >>>>> >>>>> Thanks again! >>>>> >>>>> -Colton >>>>> >>>>> On Wed, May 22, 2024 at 3:39 PM Barry Smith <[email protected]> wrote: >>>>> >>>>>> >>>>>> Are you using any other command line options or did you hardwire >>>>>> any solver parameters in the code with, like, KSPSetXXX() or PCSetXXX() >>>>>> Please send all of them. >>>>>> >>>>>> Something funky definitely happened when the true residual norms >>>>>> jumped up. >>>>>> >>>>>> Could you run the same thing with -ksp_view and don't use any thing >>>>>> like -ksp_error_if_not_converged so we can see exactly what is being run. >>>>>> >>>>>> Barry >>>>>> >>>>>> >>>>>> On May 22, 2024, at 3:21 PM, Colton Bryant < >>>>>> [email protected]> wrote: >>>>>> >>>>>> This Message Is From an External Sender >>>>>> This message came from outside your organization. >>>>>> Hello, >>>>>> >>>>>> I am solving the Stokes equations on a MAC grid discretized by finite >>>>>> differences using a DMSTAG object. I have tested the solver quite >>>>>> extensively on manufactured problems and it seems to work well. As I am >>>>>> still just trying to get things working and not yet worried about speed I >>>>>> am using the following solver options: >>>>>> -pc_type fieldsplit >>>>>> -pc_fieldsplit_detect_saddle_point >>>>>> -fieldsplit_0_pc_type lu >>>>>> -fieldsplit_1_ksp_rtol 1.e-8 >>>>>> >>>>>> However I am now using this solver as an inner step of a larger code >>>>>> and have run into issues. The code repeatedly solves the Stokes equations >>>>>> with varying right hand sides coming from changing problem geometry (the >>>>>> solver is a part of an overset grid scheme coupled to a level set method >>>>>> evolving in time). After a couple timesteps I observe the following >>>>>> output >>>>>> when running with -fieldsplit_1_ksp_converged_reason >>>>>> -fieldsplit_1_ksp_monitor_true_residual: >>>>>> >>>>>> Residual norms for back_fieldsplit_1_ solve. >>>>>> 0 KSP preconditioned resid norm 2.826514299465e-02 true resid >>>>>> norm 2.826514299465e-02 ||r(i)||/||b|| 1.000000000000e+00 >>>>>> 1 KSP preconditioned resid norm 7.286621865915e-03 true resid >>>>>> norm 7.286621865915e-03 ||r(i)||/||b|| 2.577953300039e-01 >>>>>> 2 KSP preconditioned resid norm 1.500598474492e-03 true resid >>>>>> norm 1.500598474492e-03 ||r(i)||/||b|| 5.309007192273e-02 >>>>>> 3 KSP preconditioned resid norm 3.796396924978e-04 true resid >>>>>> norm 3.796396924978e-04 ||r(i)||/||b|| 1.343137349666e-02 >>>>>> 4 KSP preconditioned resid norm 8.091057439816e-05 true resid >>>>>> norm 8.091057439816e-05 ||r(i)||/||b|| 2.862556697960e-03 >>>>>> 5 KSP preconditioned resid norm 3.689113122359e-05 true resid >>>>>> norm 3.689113122359e-05 ||r(i)||/||b|| 1.305181128239e-03 >>>>>> 6 KSP preconditioned resid norm 2.116450533352e-05 true resid >>>>>> norm 2.116450533352e-05 ||r(i)||/||b|| 7.487846545662e-04 >>>>>> 7 KSP preconditioned resid norm 3.968234031201e-06 true resid >>>>>> norm 3.968234031200e-06 ||r(i)||/||b|| 1.403932055801e-04 >>>>>> 8 KSP preconditioned resid norm 6.666949419511e-07 true resid >>>>>> norm 6.666949419506e-07 ||r(i)||/||b|| 2.358717739644e-05 >>>>>> 9 KSP preconditioned resid norm 1.941522884928e-07 true resid >>>>>> norm 1.941522884931e-07 ||r(i)||/||b|| 6.868965372998e-06 >>>>>> 10 KSP preconditioned resid norm 6.729545258682e-08 true resid >>>>>> norm 6.729545258626e-08 ||r(i)||/||b|| 2.380863687793e-06 >>>>>> 11 KSP preconditioned resid norm 3.009070131709e-08 true resid >>>>>> norm 3.009070131735e-08 ||r(i)||/||b|| 1.064586912687e-06 >>>>>> 12 KSP preconditioned resid norm 7.849353009588e-09 true resid >>>>>> norm 7.849353009903e-09 ||r(i)||/||b|| 2.777043445840e-07 >>>>>> 13 KSP preconditioned resid norm 2.306283345754e-09 true resid >>>>>> norm 2.306283346677e-09 ||r(i)||/||b|| 8.159461097060e-08 >>>>>> 14 KSP preconditioned resid norm 9.336302495083e-10 true resid >>>>>> norm 9.336302502503e-10 ||r(i)||/||b|| 3.303115255517e-08 >>>>>> 15 KSP preconditioned resid norm 6.537456143401e-10 true resid >>>>>> norm 6.537456141617e-10 ||r(i)||/||b|| 2.312903968982e-08 >>>>>> 16 KSP preconditioned resid norm 6.389159552788e-10 true resid >>>>>> norm 6.389159550304e-10 ||r(i)||/||b|| 2.260437724130e-08 >>>>>> 17 KSP preconditioned resid norm 6.380905134246e-10 true resid >>>>>> norm 6.380905136023e-10 ||r(i)||/||b|| 2.257517372981e-08 >>>>>> 18 KSP preconditioned resid norm 6.380440605992e-10 true resid >>>>>> norm 6.380440604688e-10 ||r(i)||/||b|| 2.257353025207e-08 >>>>>> 19 KSP preconditioned resid norm 6.380427156582e-10 true resid >>>>>> norm 6.380427157894e-10 ||r(i)||/||b|| 2.257348267830e-08 >>>>>> 20 KSP preconditioned resid norm 6.380426714897e-10 true resid >>>>>> norm 6.380426714004e-10 ||r(i)||/||b|| 2.257348110785e-08 >>>>>> 21 KSP preconditioned resid norm 6.380426656970e-10 true resid >>>>>> norm 6.380426658839e-10 ||r(i)||/||b|| 2.257348091268e-08 >>>>>> 22 KSP preconditioned resid norm 6.380426650538e-10 true resid >>>>>> norm 6.380426650287e-10 ||r(i)||/||b|| 2.257348088242e-08 >>>>>> 23 KSP preconditioned resid norm 6.380426649918e-10 true resid >>>>>> norm 6.380426645888e-10 ||r(i)||/||b|| 2.257348086686e-08 >>>>>> 24 KSP preconditioned resid norm 6.380426649803e-10 true resid >>>>>> norm 6.380426644294e-10 ||r(i)||/||b|| 2.257348086122e-08 >>>>>> 25 KSP preconditioned resid norm 6.380426649796e-10 true resid >>>>>> norm 6.380426649774e-10 ||r(i)||/||b|| 2.257348088061e-08 >>>>>> 26 KSP preconditioned resid norm 6.380426649795e-10 true resid >>>>>> norm 6.380426653788e-10 ||r(i)||/||b|| 2.257348089481e-08 >>>>>> 27 KSP preconditioned resid norm 6.380426649795e-10 true resid >>>>>> norm 6.380426646744e-10 ||r(i)||/||b|| 2.257348086989e-08 >>>>>> 28 KSP preconditioned resid norm 6.380426649795e-10 true resid >>>>>> norm 6.380426650818e-10 ||r(i)||/||b|| 2.257348088430e-08 >>>>>> 29 KSP preconditioned resid norm 6.380426649795e-10 true resid >>>>>> norm 6.380426649518e-10 ||r(i)||/||b|| 2.257348087970e-08 >>>>>> 30 KSP preconditioned resid norm 6.380426652142e-10 true resid >>>>>> norm 6.380426652142e-10 ||r(i)||/||b|| 2.257348088898e-08 >>>>>> 31 KSP preconditioned resid norm 6.380426652141e-10 true resid >>>>>> norm 6.380426646799e-10 ||r(i)||/||b|| 2.257348087008e-08 >>>>>> 32 KSP preconditioned resid norm 6.380426652141e-10 true resid >>>>>> norm 6.380426648077e-10 ||r(i)||/||b|| 2.257348087460e-08 >>>>>> 33 KSP preconditioned resid norm 6.380426652141e-10 true resid >>>>>> norm 6.380426649048e-10 ||r(i)||/||b|| 2.257348087804e-08 >>>>>> 34 KSP preconditioned resid norm 6.380426652141e-10 true resid >>>>>> norm 6.380426648142e-10 ||r(i)||/||b|| 2.257348087483e-08 >>>>>> 35 KSP preconditioned resid norm 6.380426652141e-10 true resid >>>>>> norm 6.380426651079e-10 ||r(i)||/||b|| 2.257348088522e-08 >>>>>> 36 KSP preconditioned resid norm 6.380426652141e-10 true resid >>>>>> norm 6.380426650433e-10 ||r(i)||/||b|| 2.257348088294e-08 >>>>>> 37 KSP preconditioned resid norm 6.380426652141e-10 true resid >>>>>> norm 6.380426649765e-10 ||r(i)||/||b|| 2.257348088057e-08 >>>>>> 38 KSP preconditioned resid norm 6.380426652141e-10 true resid >>>>>> norm 6.380426650364e-10 ||r(i)||/||b|| 2.257348088269e-08 >>>>>> 39 KSP preconditioned resid norm 6.380426652141e-10 true resid >>>>>> norm 6.380426650051e-10 ||r(i)||/||b|| 2.257348088159e-08 >>>>>> 40 KSP preconditioned resid norm 6.380426652141e-10 true resid >>>>>> norm 6.380426651154e-10 ||r(i)||/||b|| 2.257348088549e-08 >>>>>> 41 KSP preconditioned resid norm 6.380426652141e-10 true resid >>>>>> norm 6.380426650246e-10 ||r(i)||/||b|| 2.257348088227e-08 >>>>>> 42 KSP preconditioned resid norm 6.380426652141e-10 true resid >>>>>> norm 6.380426650702e-10 ||r(i)||/||b|| 2.257348088389e-08 >>>>>> 43 KSP preconditioned resid norm 6.380426652141e-10 true resid >>>>>> norm 6.380426651686e-10 ||r(i)||/||b|| 2.257348088737e-08 >>>>>> 44 KSP preconditioned resid norm 6.380426652141e-10 true resid >>>>>> norm 6.380426650870e-10 ||r(i)||/||b|| 2.257348088448e-08 >>>>>> 45 KSP preconditioned resid norm 6.380426652141e-10 true resid >>>>>> norm 6.380426651208e-10 ||r(i)||/||b|| 2.257348088568e-08 >>>>>> 46 KSP preconditioned resid norm 6.380426652141e-10 true resid >>>>>> norm 6.380426651441e-10 ||r(i)||/||b|| 2.257348088650e-08 >>>>>> 47 KSP preconditioned resid norm 6.380426652141e-10 true resid >>>>>> norm 6.380426650955e-10 ||r(i)||/||b|| 2.257348088478e-08 >>>>>> 48 KSP preconditioned resid norm 6.380426652141e-10 true resid >>>>>> norm 6.380426650877e-10 ||r(i)||/||b|| 2.257348088451e-08 >>>>>> 49 KSP preconditioned resid norm 6.380426652141e-10 true resid >>>>>> norm 6.380426651240e-10 ||r(i)||/||b|| 2.257348088579e-08 >>>>>> 50 KSP preconditioned resid norm 6.380426652141e-10 true resid >>>>>> norm 6.380426650534e-10 ||r(i)||/||b|| 2.257348088329e-08 >>>>>> 51 KSP preconditioned resid norm 6.380426652141e-10 true resid >>>>>> norm 6.380426648615e-10 ||r(i)||/||b|| 2.257348087651e-08 >>>>>> 52 KSP preconditioned resid norm 6.380426652141e-10 true resid >>>>>> norm 6.380426649523e-10 ||r(i)||/||b|| 2.257348087972e-08 >>>>>> 53 KSP preconditioned resid norm 6.380426652140e-10 true resid >>>>>> norm 6.380426652601e-10 ||r(i)||/||b|| 2.257348089061e-08 >>>>>> 54 KSP preconditioned resid norm 6.380426652125e-10 true resid >>>>>> norm 6.380427512852e-10 ||r(i)||/||b|| 2.257348393411e-08 >>>>>> 55 KSP preconditioned resid norm 6.380426651849e-10 true resid >>>>>> norm 6.380603444402e-10 ||r(i)||/||b|| 2.257410636701e-08 >>>>>> 56 KSP preconditioned resid norm 6.380426646751e-10 true resid >>>>>> norm 6.439925413105e-10 ||r(i)||/||b|| 2.278398313542e-08 >>>>>> 57 KSP preconditioned resid norm 6.380426514019e-10 true resid >>>>>> norm 2.674218007058e-09 ||r(i)||/||b|| 9.461186902765e-08 >>>>>> 58 KSP preconditioned resid norm 6.380425077384e-10 true resid >>>>>> norm 2.406759314486e-08 ||r(i)||/||b|| 8.514937691775e-07 >>>>>> 59 KSP preconditioned resid norm 6.380406171326e-10 true resid >>>>>> norm 3.100137288622e-07 ||r(i)||/||b|| 1.096805803957e-05 >>>>>> Linear back_fieldsplit_1_ solve did not converge due to >>>>>> DIVERGED_BREAKDOWN iterations 60 >>>>>> >>>>>> Any advice on steps I could take to elucidate the issue would be >>>>>> greatly appreciated. Thanks so much for any help in advance! >>>>>> >>>>>> Best, >>>>>> Colton Bryant >>>>>> >>>>>> >>>>>> >>>>> >>>> >>> >> >
