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]
> <mailto:[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]
>>> <mailto:[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]
>>> <mailto:[email protected]>> wrote:
>>>>
>>>> Use -pc_fieldsplit_0_ksp_type preonly
>>>>
>>>>
>>>>
>>>>> On May 23, 2024, at 12:43 PM, Colton Bryant
>>>>> <[email protected]
>>>>> <mailto:[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!dMycnbRyUqlSBxozlxAjTnb9HiE2xGqctU4JVMuKQoTyVcRsfBRtxvyu3T4rU5kTrXPiGcJ63yYIgp9cEefnGRE$
>>>>> 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]
>>>>> <mailto:[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]
>>>>>>> <mailto:[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]
>>>>>>> <mailto:[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]
>>>>>>>>> <mailto:[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]
>>>>>>>>> <mailto:[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]
>>>>>>>>>>> <mailto:[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
>>>>>>>>>>
>>>>>>>>
>>>>>>
>>>>
>>
