Trouble with Calculating Gamma Function Integral Convergence on Wolfram Alpha?

Click For Summary

Discussion Overview

The discussion revolves around the challenges of calculating the convergence of the gamma function integral using Wolfram Alpha. Participants explore the nature of the integral, its antiderivative, and the behavior of the integrand under various conditions.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant presents the antiderivative of the gamma function as an integral involving a logarithmic term, questioning why Wolfram Alpha struggles with convergence calculations.
  • Another participant clarifies that definite integrals do not include a constant of integration and points out that the integrand diverges at t = 0 for certain values of z, specifically when Re(z) < 1.
  • A third participant reiterates the divergence issue and emphasizes their focus on the antiderivative of the gamma function, referencing the use of Fubini's theorem in their evaluation.
  • A later reply acknowledges understanding of the previous explanation but admits to a lack of experience with Wolfram Alpha, thus unable to assist further.

Areas of Agreement / Disagreement

Participants express differing views on the nature of the integral and its evaluation, with no consensus reached regarding the specific issues with Wolfram Alpha.

Contextual Notes

There are unresolved questions regarding the assumptions made about the convergence of the integral and the specific values of z that may affect the behavior of the integrand.

Mandelbroth
Messages
610
Reaction score
23
This is mostly calculus, but the question is computer based, I think.

The antiderivative of the gamma function is, fairly trivially, ##\displaystyle \int_{0}^{+\infty}\frac{t^{z-1}}{e^{t}\ln{t}}-C##, where C is an arbitrary constant.

Why does Wolfram Alpha have trouble calculating the convergence of that integral at any given point?
 
Physics news on Phys.org
Definite integrals do not have a constant of integration. What values of z are you having trouble with? The integrand blows up at t = 0 for Re(z) <1 and the integral diverges for z = 0, -1, -2, etc.
 
mathman said:
Definite integrals do not have a constant of integration. What values of z are you having trouble with? The integrand blows up at t = 0 for Re(z) <1 and the integral diverges for z = 0, -1, -2, etc.
That's not what I'm saying. :-p

I'm saying that ##\displaystyle \int \Gamma(z) dz = \int\int_{0}^{+\infty}\frac{t^{z-1}}{e^{t}}\, dt \ dz = \int_{0}^{+\infty}\frac{t^{z-1}}{e^{t}\ln{t}}-C##. I'm evaluating the antiderivative, or "indefinite" integral, of the Gamma function. It's fairly evident that I used Fubini's theorem, because it's the only sensible way to obtain that result.

I'm asking why the antiderivative of the Gamma function can't be evaluated by Wolfram Alpha.
 
I now understand what you did. However I have never worked with Wolfram Alpha, so I can't help you there.
 

Similar threads

  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 1 ·
Replies
1
Views
3K
  • · Replies 1 ·
Replies
1
Views
3K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 200 ·
7
Replies
200
Views
31K