Can you recommend a higher order method that I might try? On Sun, Jan 19, 2020 at 10:37 AM Jed Brown <[email protected]> wrote:
> Use -ts_adapt_monitor to see the rationale. > > Note that 1bee is backward Euler with an extrapolation error estimator > (for adaptive control). It's still only first order accurate, and the > longer step may be part of your SNES issues. > > You can set a maximum time step (-ts_adapt_dt_max) or be more aggressive > about reducing time step in response to SNES failure > (-ts_adapt_scale_solve_failed) or remember that failure for longer > before increasing the step again (-ts_adapt_time_step_increase_delay) or > more gradually increase time step when permitted (-ts_adapt_clip). > > Mark Adams <[email protected]> writes: > > > I am using -ts_type arkimex -ts_arkimex_type 1bee -ts_max_snes_failures > -1 > > -ts_rtol 1e-6 -ts_dt 1.e-7 > > > > First ,Jed gave me these parameters. This is not a DAE, just a fully > > implicit solve. Advice on parameters welcome. > > > > Second, TS is reporting a large time step (0.0505357) that is wrong. > > > > Third, it repeatedly takes this extra one or two (its a 3 step method) > step > > due to SNES failure. I wonder if that can be optimized. > > > > Thanks, > > Mark > > > > > > .... > > 9 SNES Function norm 1.438395286712e-06 > > 10 SNES Function norm 8.050454869525e-07 > > Nonlinear solve converged due to CONVERGED_SNORM_RELATIVE iterations 10 > > [0] TSAdaptChoose_Basic(): Estimated scaled local truncation error > > 0.00461254, *accepting step of size 0.00304954* > > 600 TS *dt 0.0304954* time 0.697817 > > 0 SNES Function norm 1.018387577463e-02 > > ... > > 23 SNES Function norm 6.583420045281e-05 > > 24 SNES Function norm 5.959294539241e-05 > > 25 SNES Function norm 5.394347124131e-05 > > Nonlinear solve did not converge due to *DIVERGED_MAX_IT* iterations 25 > > 0 SNES Function norm 1.018387577468e-02 > > ... > > 24 SNES Function norm 1.000717662032e-06 > > 25 SNES Function norm 7.741622573808e-07 > > Nonlinear solve converged due to *CONVERGED_SNORM_RELATIVE* iterations > 25 > > 0 SNES Function norm 1.014795904701e-02 > > ... > > 15 SNES Function norm 1.334407891279e-06 > > 16 SNES Function norm 9.148934277015e-07 > > Nonlinear solve converged due to *CONVERGED_SNORM_RELATIVE* iterations > 16 > > 0 SNES Function norm 1.016588008759e-02 > > ... > > 16 SNES Function norm 9.144418053264e-07 > > Nonlinear solve converged due to *CONVERGED_SNORM_RELATIVE* iterations > 16 > > [0] TSAdaptChoose_Basic(): Estimated scaled local truncation error > > 0.0184347, *accepting step of size 0.00762384* > > 601 TS *dt 0.0505357 *time 0.705441 > > 0 SNES Function norm 1.014792968017e-02 > > 1 SNES Function norm 1.026477259201e-03 > > 2 SNES Function norm 6.170336507030e-04 > > 3 SNES Function norm 5.433176612554e-04 > > 4 SNES Function norm 5.196626557375e-04 > > 5 SNES Function norm 4.977855046309e-04 >
