TSSetEventHandler#

Sets a function used for detecting events

Synopsis#

#include "petscts.h" 
PetscErrorCode TSSetEventHandler(TS ts, PetscInt nevents, PetscInt direction[], PetscBool terminate[], PetscErrorCode (*eventhandler)(TS, PetscReal, Vec, PetscScalar[], void *), PetscErrorCode (*postevent)(TS, PetscInt, PetscInt[], PetscReal, Vec, PetscBool, void *), void *ctx)

Logically Collective

Input Parameters#

ts - the TS context obtained from TSCreate()
nevents - number of local events
direction - direction of zero crossing to be detected. -1 => Zero crossing in negative direction, +1 => Zero crossing in positive direction, 0 => both ways (one for each event)
terminate - flag to indicate whether time stepping should be terminated after event is detected (one for each event)
eventhandler - a change in sign of this function (see direction) is used to determine an even has occurred
postevent - [optional] post-event function, this function can change properties of the solution, ODE etc at the time of the event
ctx - [optional] user-defined context for private data for the event detector and post event routine (use NULL if no context is desired)

Calling sequence of `eventhandler`#

PetscErrorCode eventhandler(TS ts, PetscReal t, Vec U, PetscScalar fvalue[], void* ctx)

ts - the TS context
t - current time
U - current iterate
ctx - [optional] context passed with eventhandler
fvalue - function value of events at time t

Calling sequence of `postevent`#

PetscErrorCode postevent(TS ts, PetscInt nevents_zero, PetscInt events_zero[], PetscReal t, Vec U, PetscBool forwardsolve, void *ctx)

ts - the TS context
nevents_zero - number of local events whose event function is zero
events_zero - indices of local events which have reached zero
t - current time
U - current solution
forwardsolve - Flag to indicate whether TS is doing a forward solve (1) or adjoint solve (0)
ctx - the context passed with eventhandler

Note#

The eventhandler is actually the event detector function and the postevent function actually handles the desired changes that should take place at the time of the event