Integrals with bessel functions

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Discussion Overview

The discussion revolves around solving integrals involving Bessel functions, specifically focusing on the integral of the form int(int(exp(a*cos(theta)*sin(phi))*sin(phi), phi = 0 .. Pi), theta = 0 .. 2*Pi) and related expressions. Participants explore different approaches and tools for evaluating these integrals, including the use of Mathematica.

Discussion Character

  • Mathematical reasoning, Technical explanation, Debate/contested

Main Points Raised

  • One participant presents the integral int(int(exp(a*cos(theta)*sin(phi))*sin(phi), phi = 0 .. Pi), theta = 0 .. 2*Pi) and suggests it can be reduced to a form involving Bessel functions.
  • Another participant confirms the reduction and mentions that Mathematica provides a solution of 4*Pi*Sinh[a]/a for the integral, although the steps are not detailed.
  • A participant expresses a lack of access to Mathematica and requests assistance in solving a different integral, int(exp(a*cos(phi))*(sin(phi))^2, phi = 0 .. Pi), assuming a is a positive real constant.
  • One participant claims to have solved the integral using Mathematica, stating it equals (Pi/a)*BesselI(1,a).

Areas of Agreement / Disagreement

Participants do not reach a consensus on the solutions to the integrals discussed, as different integrals are presented and solved independently, with some relying on Mathematica while others seek manual solutions.

Contextual Notes

Some integrals are noted to be solvable by Mathematica, but the specific steps taken by the software are not provided, leading to potential gaps in understanding the reasoning behind the solutions.

Who May Find This Useful

Individuals interested in advanced integral calculus, particularly those working with Bessel functions and seeking computational tools for solving complex integrals.

areslagae
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I am trying to solve

int(int(exp(a*cos(theta)*sin(phi))*sin(phi), phi = 0 .. Pi), theta = 0 .. 2*Pi) (1)

with a a constant.

Using the second last definite integral on

http://en.wikipedia.org/wiki/List_of_integrals_of_exponential_functions

the integral (1) reduces to

2*Pi*(int(sin(phi)*BesselI(0, a*sin(phi)), phi = 0 .. Pi)) (2)

Can anyone solve (1) or (2)?
 
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areslagae said:
I am trying to solve

int(int(exp(a*cos(theta)*sin(phi))*sin(phi), phi = 0 .. Pi), theta = 0 .. 2*Pi) (1)

with a a constant.

Using the second last definite integral on

http://en.wikipedia.org/wiki/List_of_integrals_of_exponential_functions

the integral (1) reduces to

2*Pi*(int(sin(phi)*BesselI(0, a*sin(phi)), phi = 0 .. Pi)) (2)

Can anyone solve (1) or (2)?


Plugging it into Mathematica assuming a>0 gives 4*Pi*Sinh[a]/a.

It doesn't tell the steps used, unfortunately :)
 
Thanks!

Apparently, Mathematica is the only program that can solve several of the integrals I am dealing without of the box. Unfortunately, I do not have access to Mathematica.

Would you please be so kind to try if Mathematica can solve

int(exp(a*cos(phi))*(sin(phi))^2, phi = 0 .. Pi)

with a a positive real constant?
 
The integral

assume(a > 0);
int(exp(a*cos(phi))*sin(phi)^2, phi = 0 .. Pi);

equals to

(Pi/a)*BesselI(1,a)

I have solved the integral using Mathematica, which seems to solve all these integrals out of the box.
 

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