Re: Using "If" and "NDSolve" together

• To: mathgroup at smc.vnet.net
• Subject: [mg106859] Re: Using "If" and "NDSolve" together
• From: RBenf <rui.benfeitas at gmail.com>
• Date: Mon, 25 Jan 2010 05:07:15 -0500 (EST)

```Hello Bobby, thanks for all the help! It was good to see how you can simplify what I wrote into just a few coding lines. I'm still learning how to work with Mathematica, and from what I've seen, it will still be a long way until I can use it effectively.

Although the code that you gave me does not do exactly what I want to do, I will surely use it in order to solve my problem.
Thanks a lot!

> Oh, what a tangled web you weave.
>
> Clear[funcao]
> funcao[first_, last_] :=
> Module[{k0 = 10^-2, k1 = 10^-5, k2 = 10^-6, k3 =
> = 10, a, b, c},
>    a = a /. First@
> NDSolve[{a'[t] == k0 Boole[first <= t <= last]
> last] - k1 a[t],
> b'[t] == k1 a[t] - k2 b[t], c'[t] == k2 b[t]
> k2 b[t] - k3 c[t],
> a[0] == 2 10^-6, b[0] == 0, c[0] == 0}, {a,
> 0}, {a, b, c}, {t, 0,
>         1000}];
>    Plot[a@t, {t, 0, 1000}, PlotRange -> All]
>    ]
> funcao[0, 100]
> funcao[0, 900]
> funcao[100, 900]
>
> Bobby

```

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