You are right that TSEvent is not suitable for this case. To stop the timestepper, I would call TSSetConvergedReason(ts,TS_CONVERGED_USER) in a PostStep function.
Hong (Mr.) > On May 28, 2019, at 4:36 AM, Patrick Sanan via petsc-users > <petsc-users@mcs.anl.gov> wrote: > > I'm working with/on a code which uses TSSUNDIALS, and I'd like to be able to > stop the timestepper based on the value of the solution. In particular, I > wish to enforce that a given concentration has not changed by more than a > specified amount before stopping. Note that this is simpler than general > event detection, as I'm happy stopping before the condition is satisfied and > don't care about finding the point in time when the condition is satisfied > exactly. > > As far as I know, PETSc's event handling interface isn't supported with the > SUNDIALS implementation. (As an aside, I'd be happier using TSARKIMEX or > another native timestepper, but so far haven't been able to avoid tiny > timesteps). > > My question is whether the following approach has any obvious fatal flaw, and > if any TS gurus have other/better/simpler ideas. > > The idea is to add my own logic, say with TSSetPreStep(), to: > > 1. Maintain the previous step's state (this is a 1d problem, so I'm not too > concerned about the overhead of this) > 2. Check my condition, and if it's satisfied, dump the previous step's data, > and use TSSetMaxTime() with the previous step's time, thus ending the solve. >
