How Do You Integrate a Product of Bessel Functions with Polynomial Denominators?

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Discussion Overview

The discussion revolves around finding the antiderivative of a function involving products of Bessel functions with polynomial denominators. The context includes both theoretical and applied aspects, particularly in relation to calculating pavement deflections from traffic loads and subsequent derivatives for acceleration.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Experimental/applied

Main Points Raised

  • One participant presents the function \( f(x) = \frac{J_{0}(ax)J_{1}(bx)}{x+x^{4}} \) and seeks help in finding its antiderivative.
  • Another participant questions whether the answer should be expressed in terms of the Bessel function, indicating a need for clarity on the context of the problem.
  • A third participant describes a related problem involving the integral \( d(x) = \int_0^\infty \frac{J_{0}(atx)J_{1}(bt)}{t+t^{4}} \, dt \) and expresses the goal of finding the second derivative with respect to \( x \) for acceleration calculations.
  • A later reply suggests that since \( x \) only appears in the first Bessel function and not in the limits of the integral, one could differentiate that Bessel function twice with respect to \( x \) to achieve the desired result.

Areas of Agreement / Disagreement

Participants express differing views on how to approach the problem, with no consensus on the best method for finding the antiderivative or the second derivative. The discussion remains unresolved regarding the optimal approach.

Contextual Notes

There are limitations in the assumptions made about the relationship between the variables and the integrals involved. The dependence on the specific forms of the Bessel functions and the nature of the integrals may affect the outcomes.

oh20elyf
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I am struggling to find the antiderivative of the following function:f(x)=\frac{J_{0}(ax)J_{1}(bx) }{x+x^{4} } <br /> \\<br /> J_{0},{~}J_{1} : Bessel{~}function{~}of{~}the{~}first{~}kind\\<br /> a, b: constants<br /> \\<br /> F(x)=\int_{}^{} \! f(x) \, dx =?Who can help?
 
Last edited:
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oh20elyf said:
I am struggling to find the antiderivative of the following function:f(x)=\frac{J_{0}(ax)J_{1}(bx) }{x+x^{4} } <br /> \\<br /> J_{0},{~}J_{1} : Bessel{~}function{~}of{~}the{~}first{~}kind\\<br /> a, b: constants<br /> \\<br /> F(x)=\int_{}^{} \! f(x) \, dx =?Who can help?

What is the context of the question? Should the answer be in terms of the Bessel function?
 
ZaidAlyafey said:
What is the context of the question? Should the answer be in terms of the Bessel function?

Ok so the root of my problem is that i have a formula to calculate pavement deflections from traffic loads, which is the following:

d(x)=\int_0^\infty \! \frac{J_{0}(atx)J_{1}(bt)}{t+t^{4} } \, d t

a,b: constants
x: distance from load centre

Now i want to find a formula to calculate the acceleration. I have to find the second derivative of the above formula with respect of 'x'.

To do so i thought i had to get rid of the integral at first, by finding the antiderivative with respect of 't' of the equation first to be able to differentiate with respect of 'x' twice. Is there a better way to find:

\frac{d^2d(x)}{dx^2}=?
 
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Well, the only place the $x$ shows up is in the first Bessel function inside the integral. It's not even present in the limits of the integral. So, just differentiate that first Bessel function twice with respect to $x$, and you're done.
 

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