# Re: Oscillating method of integration

From: Lorenzo Moneta <Lorenzo.Moneta_at_cern.ch>
Date: Fri, 25 Aug 2006 15:50:52 +0200

Hi Andrew,

actually I noticed now you want the integral between 0 and inf. This is undefined, it is like getting the value of sin(x) for x=inf.

Best Regards,
Lorenzo

On Aug 25, 2006, at 12:49 PM, andreyk1_at_post.tau.ac.il wrote:

> Dear Lorenzo,
>
> Thanks for solution, but this is not my case. The integral is too
> complicated to
> be done analitically. The only way is numerical calculation.
> Actually I can
> integrate between BesselJ zeroes and sum up these intervals, but it
> is not
> efficient.
>
> Andrew.
>
> Quoting Lorenzo Moneta <Lorenzo.Moneta_at_cern.ch>:
>
>> Hi Andrew,
>>
>> I don't know of a method for 2d with oscillatory function.
>> Hower, you should be able for a Bessel of order 0 to solve the
>> integral analytically,
>> using the Bessel J0 definition
>>
>> see http://en.wikipedia.org/wiki/Bessel_function
>>
>> Cheers,
>>
>> Lorenzo
>> On 24 Aug 2006, at 12:14, andreyk1_at_post.tau.ac.il wrote:
>>
>>>
>>>
>>> Dear rooters,
>>>
>>> I need to integrate over two dimensionl oscillating function
>>> (TMath::BesselJ(0,x*y), 0<x<inf, 0<y<inf). I use TF1 with
>>> IntegralMultiple, but
>>> the answer is not stable, a change in max_points leads to a
>>> different result. I
>>> tried to increas the number of max_points to 1e+6 but the result is
>>> still
>>> unstable. Is there some method of integrating over oscillating
>>> function with
>>> arbitry dimensions? (in my case it is dim = 2).
>>>
>>>
>>> Thanks a lot!
>>>
>>>
>>> Andrew
>>>
>>> ----------------------------------------------------------------
>>> This message was sent using IMP, the Internet Messaging Program.
>>>
>>>
>>
>>
>> +++++++++++++++++++++++++++++++++++++++++++
>> This Mail Was Scanned By Mail-seCure System
>> at the Tel-Aviv University CC.
>>
>
>
>
>
> ----------------------------------------------------------------
> This message was sent using IMP, the Internet Messaging Program.
>
Received on Fri Aug 25 2006 - 15:53:21 MEST

This archive was generated by hypermail 2.2.0 : Mon Jan 01 2007 - 16:32:00 MET