8                      "y_dot = -0.2*x\n"
11                      "-dir    d : zero-crossing direction for events\n"
12                      "-flg      : additional output in Postevent\n"
13 …     "-errtol e : error tolerance, for printing 'pass/fail' for located events (1e-5 by default)\n"
14                      "-restart  : flag for TSRestartStep() in PostEvent\n"
15 …             "-dtpost x : if x > 0, then on even PostEvent calls 1st-post-event-step = x is set,\n"
16 …  "                            on odd PostEvent calls 1st-post-event-step = PETSC_DECIDE is set,\n"
26   PetscReal   evres[MAX_NEV];   // times of found zero-crossings
27   PetscReal   ref[MAX_NEV];     // reference times of zero-crossings, for checking
31 …errtol;           // error tolerance, for printing 'pass/fail' for located events (1e-5 by default)
33   PetscReal   dtpost;           // post-event step
56   ctx.pi      = PetscAcosReal(-1.0);  in main()
60   ctx.errtol  = 1e-5;  in main()
71   vals[2] = -0.2;  in main()
102 …PetscCall(PetscOptionsGetInt(NULL, NULL, "-dir", &dir0, NULL));             // desired zero-crossi…  in main()
103 …PetscCall(PetscOptionsHasName(NULL, NULL, "-flg", &ctx.flg));               // flag for additional…  in main()
104 …PetscCall(PetscOptionsGetReal(NULL, NULL, "-errtol", &ctx.errtol, NULL));   // error tolerance for…  in main()
105 …PetscCall(PetscOptionsGetBool(NULL, NULL, "-restart", &ctx.restart, NULL)); // flag for TSRestartS…  in main()
106   PetscCall(PetscOptionsGetReal(NULL, NULL, "-dtpost", &ctx.dtpost, NULL));   // post-event step  in main()
109   if (ctx.rank == 0) { // first event -- on rank-0  in main()
127     if (j < ctx.cntref) err = PetscAbsReal(ctx.evres[j] - ctx.ref[j]);  in main()
141   User callback for defining the event-functions
149   // for the test purposes, event-functions are defined based on t  in EventFunction()
150   // first event -- on rank-0  in EventFunction()
151   if (Ctx->rank == 0) gval[n++] = PetscSinReal(Ctx->pi * t);  in EventFunction()
156   User callback for the post-event stuff
163   if (Ctx->flg) {  in Postevent()
164     PetscCallBack("EventFunction", EventFunction(ts, t, U, Ctx->fvals, ctx));  in Postevent()
165 …, "[%d] At t = %20.16g : %" PetscInt_FMT " events triggered, fvalues =", Ctx->rank, (double)t, nev…  in Postevent()
166 …j++) PetscCall(PetscSynchronizedPrintf(PETSC_COMM_WORLD, "\t%g", (double)Ctx->fvals[evs_zero[j]]));  in Postevent()
171   if (Ctx->cnt + nev_zero < MAX_NEV)  in Postevent()
172 …for (PetscInt i = 0; i < nev_zero; i++) Ctx->evres[Ctx->cnt++] = t; // save the repeating zeros se…  in Postevent()
175   Ctx->postcnt++; // sync  in Postevent()
176   if (Ctx->dtpost > 0) {  in Postevent()
177     if (Ctx->postcnt % 2 == 0) PetscCall(TSSetPostEventStep(ts, Ctx->dtpost));  in Postevent()
182   if (Ctx->restart) PetscCall(TSRestartStep(ts));  in Postevent()
185 /*---------------------------------------------------------------------------------------------*/
187   Note, in the tests below, -ts_event_post_event_step is occasionally set to -1,
189   explicitly specify -1 in this option. Rather, if PETSC_DECIDE behaviour is needed,
193 /*TEST
194   test:
198     args: -dir 0
199     args: -restart 0
200     args: -dtpost {{0 0.25}}
201     args: -ts_event_post_event_step -1
202     args: -ts_type {{beuler rk}}
203     args: -ts_adapt_type {{none basic}}
206   test:
210     args: -dir 1
211     args: -restart 1
212     args: -dtpost {{0 0.31}}
213     args: -ts_event_post_event_step {{-1 0.25}}
214     args: -ts_type rk
215     args: -ts_adapt_type {{none basic}}
220   test:
224     args: -dir -1
225     args: -restart {{0 1}}
226     args: -dtpost {{0 0.25}}
227     args: -ts_event_post_event_step 0.31
228     args: -ts_type {{beuler rk}}
229     args: -ts_adapt_type basic
234   test:
238     args: -dir 0 -ts_event_dt_min 1e-6 -errtol 5e-5
239     args: -restart 1
240     args: -dtpost {{0 0.25}}
241     args: -ts_event_post_event_step {{-1 0.31}}
242     args: -ts_type beuler
243     args: -ts_adapt_type {{none basic}}
248   test:
252     args: -dir 1 -ts_event_dt_min 1e-6 -errtol 5e-5
253     args: -restart 0
254     args: -dtpost {{0 0.31}}
255     args: -ts_event_post_event_step 0.25
256     args: -ts_type {{beuler rk}}
257     args: -ts_adapt_type {{none basic}}
260   test:
264     args: -dir -1 -ts_event_dt_min 1e-6 -errtol 5e-5
265     args: -restart 1
266     args: -dtpost {{0 0.25}}
267     args: -ts_event_post_event_step -1
268     args: -ts_type {{beuler rk}}
269     args: -ts_adapt_type {{none basic}}
273 TEST*/