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

[Adrien Vogt-Schilb]

thank you that was it

On 07/07/2011 20:54, Stephane Mottelet wrote:
> 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
>>
>>
>
>


-- 

*Adrien Vogt-Schilb*
Research Fellow
vogt at centre-cired.fr
Tel: (+33) 1 43 94 73 96
Fax: (+33) 1 43 94 73 70

CIRED

	

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