[Octave-bug-tracker] [bug #59063] Event Handling different between Ode-Solvers (especially ode15s)

[anonymous]

URL:
  <https://savannah.gnu.org/bugs/?59063>

                 Summary: Event Handling different between Ode-Solvers
(especially ode15s)
                 Project: GNU Octave
            Submitted by: None
            Submitted on: Fri 04 Sep 2020 11:13:21 AM UTC
                Category: Octave Function
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: Michael Erhard
        Originator Email: 
             Open/Closed: Open
                 Release: 5.2.0
         Discussion Lock: Any
        Operating System: Microsoft Windows

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Details:

In cases using an event function, ode23/ode45 gives identical behaviour,
whereas ode15s (ode15i not yet tested) behaves different.

1st)
Indices of triggered events in EventFcn are counted from 1,2,3... in
ode23/ode45, whereas ode15s count from 0,1,..., if multiple constraints are
used.

2nd)
ode15s is not capable of detecting discrete time events, when the constraint
time is a multiple of the output step size. ode23/ode45 doesn't have any
problems with this

An example can be the bouncing ball problem by changing the event constraint
from state to a discrete time before ball hits the ground or by adding an
additional constraint for time.




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