Re: Integration...

• To: mathgroup at smc.vnet.net
• Subject: [mg24175] Re: Integration...
• From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
• Date: Wed, 28 Jun 2000 22:50:56 -0400 (EDT)
• Organization: Universitaet Leipzig
• References: <8jc70h\$df6@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Hi,

assuming you have dg[t] and df[t] somewhere and g[a] and f[a] are
numbers
you can use NDSolve[] with

sol=NDSolve[{f'[t]==df[t],g'[t]==dg[t],g[0]==g[a],f[0]=f[a]},{f[t],g[t]},{y,0,10^10*Pi}];

ParametricPlot[
Evaluate[{g[t],f[t]} /. sol]
{t,0,10^10 Pi}
]

Regards
Jens

"Yeung, Matthew" wrote:
>
> Dear Sir,
>
> I am a Mathematica user and am having problems with one particular task that
> I have to perform.
>
> I have 2 function, {f'(t),g'(t)}, that are unintegrable. I wish to plot the
> parametric curve {f(t),g(t)} for a<t<b, say, but do not wish to use
> NIntegrate as it will give me the result {f(T)-f(a),g(T)-g(a)}.
>
> Is there a way that I can find {f(a),g(a)} so that I can use NIntegrate; or
> is it possible to evaluate the integral at one point?
>
> Thanks for your heklp and I look forward to hearing from you soon.
>
> Regards,
>
> Matt Yeung

```

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