[petsc-dev] TSComputeRHSJacobianConstant issue
Barry Smith
bsmith at mcs.anl.gov
Wed Mar 23 17:54:07 CDT 2016
This problem still exists. What do we do? Broken code that a beginner could easily start with is not a good thing.
Barry
> On Feb 27, 2016, at 5:21 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
>
>
> Jed and Emil,
>
> Yes, this is a terrible mess. The TSComputeRHSJacobianConstant() will only work for methods that do not change entries in the Jacobian matrix. And for some reason the runex3_4 and _5 which do not work are turned off in the makefile ! It looks like Rosw does work because it does not change the matrix? And yet it is still turned off?
>
> I don't know what a good fix is. If we want to keep this capability then the TSComputeRHSJacobianConstant() interface has to keep a copy of the original user provided matrix and copy it into the matrices used by the method each time. This may lead to ugly special case code.
>
> Something has to be done about (simplest thing is just tossing the entire concept) because now there is a very broken API in TS that beginning users are likely to try and get upset with.
>
> Barry
>
>
>> On Feb 26, 2016, at 11:04 AM, Dominic Meiser <dmeiser at txcorp.com> wrote:
>>
>> Hi all,
>>
>> I'm running into problems with TS with a time independent, linear
>> rhs. Following the user's manual, I use
>>
>> ierr=TSSetProblemType(ts, TS_LINEAR);CHKERRQ(ierr);
>> ierr=TSSetRHSFunction(ts, 0, TSComputeRHSFunctionLinear, 0);CHKERRQ(ierr);
>> ierr=TSSetRHSJacobian(ts, mat, mat, TSComputeRHSJacobianConstant, 0);CHKERRQ(ierr);
>>
>> But running the code I get:
>>
>> [dmeiser at ivyamd src]$ ./sd -ts_monitor -snes_monitor -ksp_monitor_true_residual -snes_converged_reason -ts_type beuler -ts_max_steps 20 TS dt 0.01 time 0.
>> 0 SNES Function norm 1.433485640883e+00
>> 0 KSP preconditioned resid norm 1.433485640883e-02 true resid norm 1.433485640883e+00 ||r(i)||/||b|| 1.000000000000e+00
>> 1 KSP preconditioned resid norm 6.528150237447e-18 true resid norm 6.122666587510e-16 ||r(i)||/||b|| 4.271173992185e-16
>> 1 SNES Function norm 1.419007435910e+02
>> Nonlinear solve converged due to CONVERGED_ITS iterations 1
>> 1 TS dt 0.01 time 0.01
>> 0 SNES Function norm 1.433342292319e+02
>> Nonlinear solve did not converge due to DIVERGED_LINEAR_SOLVE iterations 0
>> [0]PETSC ERROR: --------------------- Error Message --------------------------------------------------------------
>> [0]PETSC ERROR:
>> [0]PETSC ERROR: TSStep has failed due to DIVERGED_NONLINEAR_SOLVE, increase -ts_max_snes_failures or make negative to attempt recovery
>> [0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html for trouble shooting.
>> [0]PETSC ERROR: Petsc Development GIT revision: pre-tsfc-330-gda8116b GIT Date: 2016-02-23 15:17:17 -0600
>> [0]PETSC ERROR: ./sd on a cplx named ivyamd.txcorp.com by dmeiser Fri Feb 26 11:46:29 2016
>> [0]PETSC ERROR: Configure options --with-scalar-type=complex --with-x=0 --with-debugging=1 --with-ssl=0 --with-fortran-kernels=0 --with-pthread=0 --download-fftw=1 --with-mpi=1 --download-mpich=1 --with-mpiuni-fortran-binding=0 --with-fortran-interfaces
>> [0]PETSC ERROR: #1 TSStep() line 3346 in /scr_ivyamd/dmeiser/SD/petsc/src/ts/interface/ts.c
>> [0]PETSC ERROR: #2 TSSolve() line 3544 in /scr_ivyamd/dmeiser/SD/petsc/src/ts/interface/ts.c
>> [0]PETSC ERROR: #3 main() line 63 in /scr_ivyamd/dmeiser/SD/src/sd.c
>> [0]PETSC ERROR: PETSc Option Table entries:
>> [0]PETSC ERROR: -ksp_monitor_true_residual
>> [0]PETSC ERROR: -snes_converged_reason
>> [0]PETSC ERROR: -snes_monitor
>> [0]PETSC ERROR: -ts_max_steps 2
>> [0]PETSC ERROR: -ts_monitor
>> [0]PETSC ERROR: -ts_type beuler
>> [0]PETSC ERROR: ----------------End of Error Message -------send entire error message to petsc-maint at mcs.anl.gov----------
>> application called MPI_Abort(MPI_COMM_WORLD, 91) - process 0
>> [unset]: aborting job:
>> application called MPI_Abort(MPI_COMM_WORLD, 91) - process 0
>>
>>
>> It seems that the linear system is being solved just fine. But
>> apparently it's the wrong linear problem because the SNES
>> function norm doesn't decrease.
>>
>> I think the problem might be related to the following behaviour
>> of `scr/ts/examples/tutorials/ex3.c`:
>>
>>
>> [dmeiser at ivyamd tutorials]$ ./ex3 -nox -ts_type beuler -ts_max_steps 2 -ksp_converged_reason -snes_monitor
>> Solving a linear TS problem on 1 processor
>> Timestep 0: step size = 0.000143637, time = 0., 2-norm error = 1.01507e-15, max norm error = 3.10862e-15
>> 0 SNES Function norm 2.018485956680e+03
>> Linear solve converged due to CONVERGED_RTOL iterations 1
>> 1 SNES Function norm 1.207665524289e+05
>> Timestep 1: step size = 0.000143637, time = 0.000143637, 2-norm error = 0.000599907, max norm error = 0.000863771
>> 0 SNES Function norm 1.195422385486e+05
>> Linear solve did not converge due to DIVERGED_PCSETUP_FAILED iterations 0
>> PCSETUP_FAILED due to FACTOR_NUMERIC_ZEROPIVOT
>> [0]PETSC ERROR: --------------------- Error Message --------------------------------------------------------------
>> [0]PETSC ERROR:
>> [0]PETSC ERROR: TSStep has failed due to DIVERGED_NONLINEAR_SOLVE, increase -ts_max_snes_failures or make negative to attempt recovery
>> [0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html for trouble shooting.
>> [0]PETSC ERROR: Petsc Development GIT revision: pre-tsfc-330-gda8116b GIT Date: 2016-02-23 15:17:17 -0600
>> [0]PETSC ERROR: ./ex3 on a cplx named ivyamd.txcorp.com by dmeiser Fri Feb 26 11:36:28 2016
>> [0]PETSC ERROR: Configure options --with-scalar-type=complex --with-x=0 --with-debugging=1 --with-ssl=0 --with-fortran-kernels=0 --with-pthread=0 --download-fftw=1 --with-mpi=1 --download-mpich=1 --with-mpiuni-fortran-binding=0 --with-fortran-interfaces
>> [0]PETSC ERROR: #1 TSStep() line 3346 in /scr_ivyamd/dmeiser/SD/petsc/src/ts/interface/ts.c
>> [0]PETSC ERROR: #2 TSSolve() line 3544 in /scr_ivyamd/dmeiser/SD/petsc/src/ts/interface/ts.c
>> [0]PETSC ERROR: #3 main() line 216 in /scr_ivyamd/dmeiser/SD/petsc/src/ts/examples/tutorials/ex3.c
>> [0]PETSC ERROR: PETSc Option Table entries:
>> [0]PETSC ERROR: -ksp_converged_reason
>> [0]PETSC ERROR: -nox
>> [0]PETSC ERROR: -snes_monitor
>> [0]PETSC ERROR: -ts_max_steps 2
>> [0]PETSC ERROR: -ts_type beuler
>> [0]PETSC ERROR: ----------------End of Error Message -------send entire error message to petsc-maint at mcs.anl.gov----------
>> application called MPI_Abort(MPI_COMM_WORLD, 91) - process 0
>> [unset]: aborting job:
>> application called MPI_Abort(MPI_COMM_WORLD, 91) - process 0
>>
>>
>> I'm aware of Jed's commit e1244c6 which I thought was supposed to
>> enable constant linear rhs without IFunction and IJacobian. Note
>> that e1244c6 also added tests that apparently produced very
>> different output (see e.g.
>> src/ts/examples/tutorials/output/ex3_4.out).
>>
>> Is constant rhs without IFunction and IJacobian no longer
>> supported or did it just breat at some point? Do I need to call
>> TSRHSJacobianSetReuse in addition to the lines of code above? Is
>> it better to treat such systems using TSComputeIFunctionLinear
>> and TSComputeIJacobianConstant?
>>
>> Thanks,
>> Dominic
>>
>> --
>> Dominic Meiser
>> Tech-X Corporation - 5621 Arapahoe Avenue - Boulder, CO 80303
>
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