Re: NIntegrate of Oscillatory integrand
- To: mathgroup at smc.vnet.net
- Subject: [mg94295] Re: NIntegrate of Oscillatory integrand
- From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
- Date: Wed, 10 Dec 2008 04:43:57 -0500 (EST)
- Organization: The Open University, Milton Keynes, UK
- References: <ghlml2$km8$1@smc.vnet.net>
ventutech at gmail.com wrote:
> Do someone has an idea how can I do the numerical integral
>
> Int_0_to_inf (1/p)( Cos[ A - k t] - Cos[ A - k f(k) t]) where f(k) is
> an arbitrary decreasing function (besselK0, or just a gaussian..)
>
> Oscillatory and DoubleExponential methods don't work...
Please, could you post an example in full Mathematica syntax of what you
actually tried (and possibly the associated expected result)?
Meanwhile, have you tried some options such as MaxRecursion? For
instance (assuming I have correctly interpreted your "code"),
With[{p = 2, A = 3, k = 1},
Module[{f, intg},
f[k_] = BesselK[0, k];
intg = (1/p) (Cos[A - k t] - Cos[A - k f[k] t]);
Print[Plot[intg, {t, 0, 1000}]];
NIntegrate[intg, {t, 0, Infinity}, MaxRecursion -> 20,
Method -> "DoubleExponential"]
]
]
Regards,
-- Jean-Marc