[petsc-users] TS (arkimex) question

[Mark Adams]

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
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20200119/a1340ab7/attachment.html>