Re: Using InterpolatingFunction in Argument of NIntegrate

• To: mathgroup at smc.vnet.net
• Subject: [mg57802] Re: Using InterpolatingFunction in Argument of NIntegrate
• From: "Jens-Peer Kuska" <kuska at informatik.uni-leipzig.de>
• Date: Thu, 9 Jun 2005 05:17:35 -0400 (EDT)
• Organization: Uni Leipzig
• References: <d8691p\$c70\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Hi,

f[t_?NumericQ] =
x[t] /. NDSolve[

{x''[t] + x[t] == 0, x[0] == 0, x'[0]
== 1},

x[t], {t, 0, 2Pi}][[1]]

Plot[f[t], {t, 0, 2Pi}]

NIntegrate[f[t], {t, 0, Pi}]

??

Regards

Jens

"Iggy" <blah at blah.com> schrieb im Newsbeitrag
news:d8691p\$c70\$1 at smc.vnet.net...
> Hi,
>
> I am solving numberically an ODE and outputing
> the results into a function
> f(x). This f(x) is some InterpolatingFunction.
>
> I would like to then use f(x) in a call to
> NIntegrate in a way such as:
>
> NIntegrate[g(f(x),{x,0,1}]
>
> However I get an integrand not numerical error.
> I can easily Plot g(f(x))
> and if I replace f(x) with some function like
> x^2 everything works too.
>
> How can I get around this?
>
> Thanks,
>
> Iggy
>

```

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