291   MonitorCtx *mon = (MonitorCtx *)ctx;  in MonitorError()  local
295   if (!mon->problem->solution) PetscFunctionReturn(PETSC_SUCCESS);  in MonitorError()
296   PetscCall((*mon->problem->solution)(t, mon->x, mon->problem->data));  in MonitorError()
298   PetscCall(VecNorm(mon->x, NORM_2, &nrm_exact));  in MonitorError()
299   PetscCall(VecAYPX(mon->x, -1, x));  in MonitorError()
300   PetscCall(VecNorm(mon->x, NORM_2, &nrm_diff));  in MonitorError()
302   if (step < 0) PetscCall(PetscPrintf(mon->comm, "Interpolated final solution "));  in MonitorError()
303 …PetscCall(PetscPrintf(mon->comm, "step %4" PetscInt_FMT " t=%12.8e h=% 8.2e  |x|=%9.2e  |x_e|=%9.2…  in MonitorError()
319   MonitorCtx        mon;  in main()  local
370   mon.comm    = PETSC_COMM_WORLD;  in main()
371   mon.problem = problem;  in main()
372   PetscCall(VecDuplicate(x, &mon.x));  in main()
386   if (use_monitor) PetscCall(TSMonitorSet(ts, &MonitorError, &mon, NULL));  in main()
421   PetscCall(VecDestroy(&mon.x));  in main()