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Re: NDSolve:StoppingTest in Algebraic Differential Equations

• To: mathgroup at smc.vnet.net
• Subject: [mg67145] Re: [mg67071] NDSolve:StoppingTest in Algebraic Differential Equations
• From: bsyehuda at gmail.com
• Date: Sat, 10 Jun 2006 04:54:08 -0400 (EDT)
• References: <200606080854.EAA12425@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

To the best of my knowledge, this is not implemented yet for
differential-algebraic equations.
yehuda

On 6/8/06, ben <benjamin.friedrich at gmail.com> wrote:
>
> Hi,
>
> I discovered a strange behaviour of StoppingTest:
>
> * for an ordinary differential equation everything is fine
>
>   NDSolve[{y'[t] == 1, y[0] == 0}, {y}, {t, 0, 2}, StoppingTest ->
> {y[t] > 1}]
>
> * but even for simple algebraic differential equations,
>
>   NDSolve[{y'[t] == 1, x[t] == y[t], y[0] == 0}, {x, y}, {t, 0, 2},
>   StoppingTest -> {y[t] > 1}]
>
>   I get an error message
>
>   "Unable to create a NumericalFunction for the expression
>   Hold[{y[t] > 1}]
>   in the method "EventLocator".
>
> Any suggestions?
>
> Cheers,
> Ben
>
>

• References:
  • NDSolve:StoppingTest in Algebraic Differential Equations
    • From: "ben" <benjamin.friedrich@gmail.com>