Solving Integrals from Hell for n = 1, 1/2, 2, 3/2

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Discussion Overview

The discussion revolves around the analytical solvability of a specific integral involving parameters \( \omega \), \( \phi \), and \( \lambda \), for various values of \( n \) (1, 1/2, 2, 3/2). The scope includes theoretical exploration of integral calculus and potential restrictions on parameters affecting convergence.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant questions whether the integral can be solved analytically or if approximations are necessary.
  • Another participant inquires about potential restrictions on parameters, specifically whether \( \omega \), \( \phi \), and \( \lambda \) are real and positive.
  • A participant suggests that if \( \lambda = 0 \), then the real part of \( \phi \) must be negative for the integral to converge.
  • One participant expresses uncertainty about the existence of restrictions and mentions that the integral was posed by a friend, indicating a lack of familiarity with the context of the problem.
  • There is a suggestion that the integral's complexity may be unusual compared to typical practical problems encountered.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the existence of restrictions for the parameters involved in the integral. Multiple viewpoints are presented regarding the necessity and implications of such restrictions.

Contextual Notes

The discussion highlights the potential for convergence issues based on parameter values, but specific mathematical steps or assumptions regarding the integral's solvability remain unresolved.

l'Hôpital
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Hi, I was just wondering if these integrals could be solved analytically, or if I would just have to resort to approximations.

[tex] \int_{0}^{\infty} \sqrt{1 + \omega E^2} E^n ln(1 + \omega E^2) \frac{e^{\phi E}}{(\lambda e^{\phi E} + 1)^2} dE[/tex]

For

[tex] n = 1, 1/2, 2, 3/2[/tex]
 
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any restrictions on any parameters? For example, is it true that [tex]\omega[/tex] is real and positive? Is [tex]\phi[/tex] real? Any restrictions on [tex]\lambda[/tex]?
 
No restrictions. But if you'd like to set some, go for it.

I'd just rather avoid approximation unless they wouldn't perturb the value by much.
 
Surely there must be some restrictions. For example, if [tex]\lambda = 0[/tex] then the real part of [tex]\phi[/tex] must be negative, otherwise the integral doesn't converge. Are there any special cases that are particularly interesting?

I am playing with it, but don't have my hopes up.

By the way, where did this integral come from? It is unusual to have so many arbitrary parameters (meaning all can be arbitrary complex numbers) in the practical problems I usually run into. jason
 
Truth be told, I don't know if there are any restrictions.

A friend asked me for my opinion on these integrals, if there was a way to solve them analytically. Of course, I was stumped, so I figured I'd do him the favor of posting these up in PF.

I'll try to see if I can find some restrictions on them.
 

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