[Octave-bug-tracker] [bug #49190] no return to prompt by ode45() when blowup of solution occurs

[Carlo de Falco]

Update of bug #49190 (project octave):

             Assigned to:                    None => cdf                    

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Follow-up Comment #1:

Hi,

Thanks for reporting this.

I tested the same example in Matlab
and it seems what happens there is
that the simulation is stopped issuing
a warning when the timestep becomes too
small.

I was not able to find documentation 
of the value being set for the minimum
timestep though. Some testing seems to 
indicate this is problem dependent ...


[t,x]=ode45(@(t,x)2*(1+x.^2),[0,2],0);
Warning: Failure at t=7.853880e-01.  Unable to meet integration tolerances
without reducing the step size below the smallest value allowed
(1.776357e-15) at time t. 
> In ode45 (line 308) 
>> [t,x]=ode45(@(t,x)1+x.^2,[0,2],0);
Warning: Failure at t=1.570767e+00.  Unable to meet integration tolerances
without reducing the step size below the smallest value allowed
(3.552714e-15) at time t. 
> In ode45 (line 308) 


any idea what would be a reasonable to select this value?

c.


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