I understand. Thanks again.
On Thu, Jun 18, 2015 at 10:58 PM, Emil Constantinescu <[email protected]> wrote: > The results enclosed for 3.5.4 (354.txt) are not correct. I can tell that > by looking at the first step. Most implicit schemes in arkimex have the > first stage explicit and therefore need to be "started" somehow when > dealing with algebraic constraints. In this case, a different scheme is > used to start the integration. > > Note that in 3.6 and 3.5.4_SEGV the first step uses scheme 1bee > (scheme=0:'1bee') and then switches to '3'. This is the correct sequence > otherwise inconsistent initial conditions are inadvertently used or the > solver thinks it solves an ODE. I'm not sure why it's crashing in > 3.5.4_SEGV. Configuring with --with-debugging=yes may reveal more. > > Emil > > On 6/18/15 4:10 PM, Italo Tasso wrote: > >> Thank you Barry and Emil. >> >> It works, but it takes twice as many steps than before. >> >> Was it wrong before? Should I have been using this option all along? >> >> I am solving the Navier-Stokes equations, full implicit and non-linear. >> >> I also noticed two things: >> >> In the 3.6.0 output, ts_monitor skips timestep #1. >> >> If I use the equation type in 3.5.4, I get segmentation fault. >> >> I attached the outputs. >> >> >> >> >> >> On Thu, Jun 18, 2015 at 1:24 PM, Emil Constantinescu >> <[email protected] <mailto:[email protected]>> wrote: >> >> No, I'm not sure if it should. It belongs to the same category as >> "problem_type" == TS_LINEAR / == TS_NONLINEAR. >> >> Emil >> >> >> On 6/18/15 11:15 AM, Abhyankar, Shrirang G. wrote: >> >> Can the DAE equation type be supplied via a run-time option? >> >> Shri >> >> -----Original Message----- >> From: barry smith <[email protected] <mailto:[email protected] >> >> >> Date: Thursday, June 18, 2015 at 11:08 AM >> To: Italo Tasso <[email protected] >> <mailto:[email protected]>>, "Constantinescu, Emil M." >> <[email protected] <mailto:[email protected]>> >> Cc: "[email protected] <mailto:[email protected]>" >> <[email protected] <mailto:[email protected]>> >> Subject: Re: [petsc-users] arkimex rejecting all dt in petsc 3.6.0 >> >> >> Here is the response from Emil who made the changes to >> the code >> >> If you are solving a DAE then in the new version, we >> introduced a new >> flag that distinguishes between ODEs and DAEs leading to >> different >> semantics. For DAEs this is needed b/c it may not have >> consistent initial >> conditions. >> >> If solving DAEs, the user has to set the EquationType >> appropriately: >> e.g., >> ierr = >> TSSetEquationType(ts,TS_EQ_DAE_IMPLICIT_INDEX1);CHKERRQ(ierr); >> >> This is documented in the doc, but I didn't add it to the >> changelog (Jed >> pointed it out to me). >> >> Currently it only affects -ts_type arkimex. I'll work with >> Satish to add >> it to the changelog. >> >> *If that's not the case:* let me know and we can dig deeper. >> >> Emil >> >> On Jun 18, 2015, at 5:48 AM, Italo Tasso >> <[email protected] <mailto:[email protected]>> wrote: >> >> I just upgraded to 3.6.0 and my code stopped working. >> All dt are >> rejected. I used the same configure line, same code, >> same everything. >> >> With 3.5.4 I get: >> >> 0 TS dt 1e-06 time 0 >> 0 SNES Function norm 2.549981005316e+05 >> 1 SNES Function norm 6.107056905987e-03 >> 2 SNES Function norm 1.483881932064e-10 >> 3 SNES Function norm 9.122873794272e-11 >> Nonlinear solve converged due to CONVERGED_FNORM_ABS >> iterations 3 >> 0 SNES Function norm 7.790429171165e+04 >> 1 SNES Function norm 7.289068747803e-04 >> 2 SNES Function norm 8.227639633330e-11 >> Nonlinear solve converged due to CONVERGED_FNORM_ABS >> iterations 2 >> 0 SNES Function norm 1.154356516184e+05 >> 1 SNES Function norm 2.309925413255e-03 >> 2 SNES Function norm 6.382141981406e-11 >> Nonlinear solve converged due to CONVERGED_FNORM_ABS >> iterations 2 >> TSAdapt 'basic': step 0 accepted t=0 >> + 1.000e-06 >> wlte=0.000654 family='arkimex' scheme=0:'3' dt=1.000e-05 >> >> With 3.6.0 I get: >> >> 0 TS dt 1e-06 time 0 >> 0 SNES Function norm 2.549981005316e+05 >> 1 SNES Function norm 6.107056925316e-03 >> 2 SNES Function norm 1.519319591792e-10 >> 3 SNES Function norm 9.070104116945e-11 >> Nonlinear solve converged due to CONVERGED_FNORM_ABS >> iterations 3 >> 0 SNES Function norm 7.790429171165e+04 >> 1 SNES Function norm 6.942541792651e-04 >> 2 SNES Function norm 8.458781909516e-11 >> Nonlinear solve converged due to CONVERGED_FNORM_ABS >> iterations 2 >> 0 SNES Function norm 1.154356516184e+05 >> 1 SNES Function norm 2.287202942961e-03 >> 2 SNES Function norm 6.585201377573e-11 >> Nonlinear solve converged due to CONVERGED_FNORM_ABS >> iterations 2 >> TSAdapt 'basic': step 0 rejected t=0 >> + 1.000e-06 wlte= >> 324 family='arkimex' scheme=0:'3' dt=1.311e-07 >> >> Any ideas? I attached the full output. >> >> Options I use: >> >> -ts_view -ts_type arkimex -ts_arkimex_fully_implicit >> -ts_adapt_monitor >> -ts_monitor -snes_monitor -snes_converged_reason >> -ksp_type preonly >> -pc_type lu -pc_factor_mat_solver_package mumps >> -snes_rtol 0 -snes_atol >> 1e-10 -snes_stol 0 >> >> <petsc354.txt><petsc360.txt> >> >> >> >> >>
