[scilab-Users] terminating a numerical integration when y reaches a value (instead of t as with ode)

[Stephane Mottelet]

Hello,

use the "root" parameter of ode (it is well explained in the help page  
of this macro).

S.

Adrien Vogt-Schilb <vogt at centre-cired.fr> a écrit :

> Hi everyone,
>
> When one whishes to solve an ODE y'=f(t,y) starting at point (t0,y0), one
> can use the ode function with the following arguments ode(y0,t0, [t0:tf], f),
> where [t0:tf] is the interval on which one wants to solve the ODE.
>
> The terminal condition of the resolution is, in the ode function, a time
> condition (t==tf). Does anybody know if and how we can use instead a  
> terminal condition on y?
>
>
> Let us suppose, for example, that we know that the solution increases to
> infinity (maybe in finite time). The problem is to solve the ODE as long
> as y stays under a certain value yf. We do not know which temporal  
> interval is to
> be used to reach this yf.
>
> Numerical example: we want to solve y'=1+a.*y^3 from y0=0 to yf=10 for
> differents values of a.
>
> Any ideas ?
>
>
> Best regards,
> Adrien
>
> AVS
>
>