[petsc-users] TSSetTimeStep or -ts_dt not working

[Mark Adams]

Try running with -ts_view and -options_left and send all of the output.

On Wed, Oct 11, 2017 at 1:12 PM, Ali Berk Kahraman <
aliberkkahraman at yahoo.com> wrote:

> Hello All,
>
>
> I am trying to use timesteppers, however I have a problem. Whenever I want
> to set a dt for the timstepping integration, I cannot succeed. Neither the
> function TSSetTimeStep nor the command line option seems to work. Using
> either of them(but not at the same time) and setting it to 1, when I call
> TSGetTimeStep to learn the value of dt, it gives me the answer 0.002871.
> Perhaps this is the default value, however I cannot work with this, since
> the equation I have is slowly evolving.
>
>
> Any ideas what might be causing this?
>
>
> The part of the code I use,
>
>
> PetscReal time=0, timestep=1;
>     int maxsteps=30;
>     float maxtime=300;
>
>
>         TS ts;
>         ierr= TSCreate(PETSC_COMM_WORLD,&ts);
>         CHKERRQ(ierr);
>         ierr= TSSetProblemType(ts,TS_LINEAR);
>         CHKERRQ(ierr);
>         ierr= TSSetSolution(ts, dummyvec);
>         CHKERRQ(ierr);
>         ierr= TSSetType(ts,TSRK);
>         CHKERRQ(ierr);
>         ierr= TSSetTime(ts,time);
>         CHKERRQ(ierr);
>         ierr= TSSetTimeStep(ts,timestep);
>         CHKERRQ(ierr);
>         ierr=TSSetExactFinalTime(ts,TS_EXACTFINALTIME_STEPOVER);
>         CHKERRQ(ierr);
>         TSSetMaxSteps(ts,maxsteps);
>         TSSetMaxTime(ts,maxtime);
>
>         ierr=TSSetFromOptions(ts);CHKERRQ(ierr);
>         TSSetRHSFunction(ts,residual,
>                          FormRHSFunction,&mycontext);
>         ierr= TSSolve(ts,uJi);
>         CHKERRQ(ierr);
>         TSView(ts,PETSC_VIEWER_STDOUT_SELF);
>
>         TSConvergedReason reason;
>         ierr=TSGetConvergedReason(ts,&reason);CHKERRQ(ierr);
>         printf("Why Converged: %d\n",reason);
>         PetscReal usedtimestep;
>         TSGetTimeStep(ts,&usedtimestep);
>         printf("Used timestep: %f\n",usedtimestep);
>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20171011/26a840b3/attachment.html>