Okay, so you start your integration with "TSSetMaxTime and then call TSSolve (TSSetExactFinalTime is set to TS_EXACTFINALTIME_MATCHSTEP)"
Then after it's done at t=2 you tell TS that TSSetTimeStep(ts,1e-3) and call TSSolve again? Emil On 12/13/18 11:36 AM, Zhang, Hong via petsc-users wrote: > Please make sure your messages go to petsc-users when replying. > >> On Dec 13, 2018, at 11:25 AM, moritz.h...@isea.rwth-aachen.de >> <mailto:moritz.h...@isea.rwth-aachen.de> wrote: >> >> The first solve to 1e-3 >> TSAdapt basic arkimex 0:1bee step 0 rejected t=0 + >> 1.000e-03 dt=1.000e-04 wlte= 102 wltea= -1 wlter= -1 >> TSAdapt basic arkimex 0:1bee step 0 rejected t=0 + >> 1.000e-04 dt=1.000e-05 wlte= 127 wltea= -1 wlter= -1 >> TSAdapt basic arkimex 0:1bee step 0 rejected t=0 + >> 1.000e-05 dt=1.995e-06 wlte= 5.09 wltea= -1 wlter= -1 >> TSAdapt basic arkimex 0:1bee step 0 accepted t=0 + >> 1.995e-06 dt=3.232e-06 wlte=0.309 wltea= -1 wlter= -1 >> TSAdapt basic arkimex 0:4 step 1 accepted t=1.99488e-06+ >> 3.232e-06 dt=3.232e-05 wlte=1.65e-06 wltea= -1 wlter= -1 >> TSAdapt basic arkimex 0:4 step 2 accepted t=5.22663e-06+ >> 3.232e-05 dt=3.232e-04 wlte=3.96e-05 wltea= -1 wlter= -1 >> TSAdapt basic arkimex 0:4 step 3 accepted t=3.75441e-05+ >> 3.232e-04 dt=6.393e-04 wlte=0.000973 wltea= -1 wlter= -1 >> TSAdapt basic arkimex 0:4 step 4 accepted t=0.000360719+ >> 6.393e-04 dt=2.962e-03 wlte=0.00142 wltea= -1 wlter= -1 >> the solve steps afterwards: >> TSAdapt basic arkimex 0:4 step 5 accepted t=0.001 + >> 2.962e-03 dt=7.110e-03 wlte=0.0197 wltea= -1 wlter= -1 >> TSAdapt basic arkimex 0:4 step 6 accepted t=0.00396151 + >> 7.110e-03 dt=2.489e-02 wlte=0.00437 wltea= -1 wlter= -1 >> TSAdapt basic arkimex 0:4 step 7 accepted t=0.0110717 + >> 2.489e-02 dt=7.079e-02 wlte= 0.01 wltea= -1 wlter= -1 >> TSAdapt basic arkimex 0:4 step 8 accepted t=0.03596 + >> 7.079e-02 dt=9.672e-02 wlte=0.188 wltea= -1 wlter= -1 >> TSAdapt basic arkimex 0:4 step 9 accepted t=0.106753 + >> 9.672e-02 dt=1.329e-01 wlte=0.184 wltea= -1 wlter= -1 >> around here it reaches a steady state >> TSAdapt basic arkimex 0:4 step 10 accepted t=0.203478 + >> 1.329e-01 dt=2.432e-01 wlte=0.0586 wltea= -1 wlter= -1 >> TSAdapt basic arkimex 0:4 step 11 accepted t=0.336424 + >> 2.432e-01 dt=4.536e-01 wlte=0.0542 wltea= -1 wlter= -1 >> TSAdapt basic arkimex 0:4 step 12 accepted t=0.579616 + >> 4.536e-01 dt=1.112e+00 wlte=0.0182 wltea= -1 wlter= -1 >> TSAdapt basic arkimex 0:4 step 13 accepted t=1.03324 + >> 9.668e-01 dt=3.286e+00 wlte=0.00492 wltea= -1 wlter= -1 >> here I set the timestep to 1e-3 artificially and the solution deviates >> from the steady state solution > > The TS time jumps between step 13 and step 14, which is probably the > cause of the jump in the solution. > Did you reset the time to t=2 by calling TSSetTime() after step 13? > > Hong > >> TSAdapt basic arkimex 0:4 step 14 accepted t=2 + >> 1.000e-03 dt=3.845e-03 wlte=0.003 wltea= -1 wlter= -1 >> TSAdapt basic arkimex 0:4 step 15 accepted t=2.001 + >> 3.845e-03 dt=3.845e-02 wlte=6.95e-06 wltea= -1 wlter= -1 >> TSAdapt basic arkimex 0:4 step 16 accepted t=2.00485 + >> 3.845e-02 dt=3.845e-01 wlte=4.31e-05 wltea= -1 wlter= -1 >> TSAdapt basic arkimex 0:4 step 17 accepted t=2.0433 + >> 3.845e-01 dt=2.473e+00 wlte=0.000384 wltea= -1 wlter= -1 >> TSAdapt basic arkimex 0:4 step 18 accepted t=2.42784 + >> 2.473e+00 dt=4.540e+00 wlte=0.0578 wltea= -1 wlter= -1 >> this point is "back on track" >> TSAdapt basic arkimex 0:4 step 19 accepted t=4.90058 + >> 4.540e+00 dt=4.649e+00 wlte=0.596 wltea= -1 wlter= -1 >> *Von:*Zhang, Hong <hongzh...@anl.gov <mailto:hongzh...@anl.gov>> >> *Gesendet:*Donnerstag, 13. Dezember 2018 17:39 >> *An:*Huck, Moritz <moritz.h...@isea.rwth-aachen.de >> <mailto:moritz.h...@isea.rwth-aachen.de>> >> *Cc:*petsc-users@mcs.anl.gov <mailto:petsc-users@mcs.anl.gov> >> *Betreff:*Re: [petsc-users] Solution "jumps" after setting timestep >> Can you show the outputs of -ts_monitor for both cases (one with >> oscillations and one without)? >> Thanks, >> Hong >> >> >> On Dec 13, 2018, at 9:48 AM,moritz.h...@isea.rwth-aachen.de >> <mailto:moritz.h...@isea.rwth-aachen.de>wrote: >> Hi, >> Sure after reaching a steady state it looks like this: >> 0 SNES Function norm 3.767377637168e-03 >> 1 SNES Function norm 2.529971638368e-05 >> 2 SNES Function norm 4.433873358247e-09 >> 3 SNES Function norm 4.535675922104e-11 >> 0 SNES Function norm 9.898938706929e-04 >> 1 SNES Function norm 1.322473621975e-05 >> 2 SNES Function norm 1.672724799379e-09 >> 3 SNES Function norm 1.338501638801e-11 >> 0 SNES Function norm 1.624500221071e-03 >> 1 SNES Function norm 2.448515345247e-05 >> 2 SNES Function norm 6.225549426481e-09 >> 3 SNES Function norm 1.062516222150e-10 >> 4 SNES Function norm 6.493758120241e-13 >> 0 SNES Function norm 1.106311709708e-03 >> 1 SNES Function norm 2.475673243430e-05 >> 2 SNES Function norm 9.969586735411e-09 >> 3 SNES Function norm 2.479591395229e-10 >> 4 SNES Function norm 1.542689576708e-12 >> 0 SNES Function norm 6.070943996748e-04 >> 1 SNES Function norm 1.648134285171e-05 >> 2 SNES Function norm 8.461078655420e-09 >> 3 SNES Function norm 2.480863447790e-10 >> 4 SNES Function norm 1.513977618851e-12 >> TSAdapt basic arkimex 0:4 step 15 accepted t=5.67201 + >> 4.328e+00 dt=4.687e+00 wlte$ >> 0.477 wltea= -1 wlter= -1 >> If I set the next target time (in tssolve) to be tlast+1e-3 it >> looks like this: >> 0 SNES Function norm 4.734802409365e-03 >> 1 SNES Function norm 6.173939866359e-13 >> 0 SNES Function norm 5.633294284900e-04 >> 1 SNES Function norm 3.575533754564e-13 >> 0 SNES Function norm 9.651618110271e-04 >> 1 SNES Function norm 6.863177319359e-13 >> 0 SNES Function norm 7.706102281617e-04 >> 1 SNES Function norm 8.490865565002e-13 >> 0 SNES Function norm 5.028108294534e-04 >> 1 SNES Function norm 6.905750968862e-13 >> TSAdapt basic arkimex 0:4 step 16 accepted t=10 + >> 1.000e-03 dt=2.612e-03 wlte$ >> 0.0141 wltea= -1 wlter= -1 >> The SNES solver has a atoll of 1e-10, setting the atoll to lower >> values does not change the result. >> Thank you, >> Moritz >> *Von:*Zhang, Hong <hongzh...@anl.gov <mailto:hongzh...@anl.gov>> >> *Gesendet:*Donnerstag, 13. Dezember 2018 16:42 >> *An:*Huck, Moritz <moritz.h...@isea.rwth-aachen.de >> <mailto:moritz.h...@isea.rwth-aachen.de>> >> *Cc:*petsc-users@mcs.anl.gov <mailto:petsc-users@mcs.anl.gov> >> *Betreff:*Re: [petsc-users] Solution "jumps" after setting timestep >> Can you please add command line options -ts_monitor -snes_monitor >> and show us the outputs? >> Thanks, >> Hong (Mr.) >> >> >> >> On Nov 4, 2018, at 6:19 AM, Moritz.Huck--- via petsc-users >> <petsc-users@mcs.anl.gov <mailto:petsc-users@mcs.anl.gov>> wrote: >> Hi, >> >> I using the basic adaptor. >> If I let the adaptor handle everything it does not oscillates. >> I don’t mean setting the timestep at the start (which does not >> produces the >> problem), >> I need to set during runtime between two steps. >> >> Best Regards, >> >> Moritz >> >> -----Ursprüngliche Nachricht----- >> Von: Constantinescu, Emil M. <emcon...@anl.gov >> <mailto:emcon...@anl.gov>> >> Gesendet: Samstag, 3. November 2018 15:43 >> An: Huck, Moritz <moritz.h...@isea.rwth-aachen.de >> <mailto:moritz.h...@isea.rwth-aachen.de>>;petsc-users@mcs.anl.gov >> <mailto:petsc-users@mcs.anl.gov> >> Betreff: Re: [petsc-users] Solution "jumps" after setting timestep >> >> On 11/3/18 4:56 AM, Moritz.Huck--- via petsc-users wrote: >> >> >> Hi, >> >> I am using the IMEX Runge Kutta to solve an implicit DAE >> (G=0). >> >> When I manually set the time step (TSSetTimestep) my >> solution jumps. >> >> >> When you don't set the time step, does it still oscillates? If >> not, can you >> check if it oscillates when reducing the fixed initial time step? >> Did you turn the adaptivity off (-ts_adapt_type none)? >> >> Emil >> >> >> >> >> If I go from a steady state to the same state, it >> oscillates a few >> time and comes back to the steady solution. >> >> Can this be prevented? >> >> Thank you, >> >> Moritz >> >