[Octave-bug-tracker] [bug #49919] ode45 event problem, event active at initial time

[Bill Greene]

Follow-up Comment #4, bug #49919 (project octave):

Possibly I have mis-diagnosed the root cause of the problem.
But, yes, I think bug #49846 is either the same problem or
closely related.

A matlab doc that discusses this "first step" issue is
https://www.mathworks.com/help/matlab/math/ode-event-location.html
under the section "Limitations"

This example is from Moler's book Numerical Computing With Matlab
If you look on page 26 of this doc
https://www.mathworks.com/content/dam/mathworks/mathworks-dot-com/moler/odes.pdf
you will see what (apparently) matlab returns for this example.
As you can see from the figure, matlab terminates when the solution
gets back to y=0 the second time around.

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