Double Integral: solution with hypergeometric function?

In summary, the conversation discusses a double integral with given conditions and explores the possibility of using a formula from a reference book to solve it. However, there are concerns about the validity of the formula and potential divergence of the integral at certain values.
  • #1
Dirickby
3
1

Homework Statement


Hello, I've recently encountered this double integral
$$\int_0^1 dv \int_0^1 dw \frac{(vw)^n(1-v)^m}{(1-vw)^\alpha} $$

with ## \Re(n),\Re(m) \geq 0## and ##\alpha = 1,2,3##.

Homework Equations



I use Table of Integrals, Series and Products by Gradshteyn & Ryzhik as a reference. There I found that
$$\int_0^1 dv \frac{(v)^n(1-v)^m}{(1-vw)^\alpha} = \beta(n+1, m+1)
_2F_1(\alpha ,n+1; n+m+2; w) \qquad\text{(3.197.3)} $$
with the ##\beta##-function and ##_2F_1## the ordinary hypergeometric function. But this equation is only valid for ##w<1## (and ## \Re(n+1),\Re(m+1) > 0##, which is the case here).

The Attempt at a Solution


If I could use the formula above, I could easily integrate over ##v## and then over ##w##, but I suppose it would be wrong as ##w=1## at the upper integration limit. Can I somehow bypass this?
Additionnally if we were to only consider ##w=1##, the integral would diverge at least in some cases (e.g. ##m=0##). Could my whole integral diverge because of this?
 
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  • #2
At w=1, the integral from Gradstein diverges logarithmically. But the integral over a logarithmic singularity is finite, so the integral over w should exist.
 
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1. What is a double integral?

A double integral is a type of mathematical operation that involves integrating a function of two variables over a specific region in a two-dimensional space. It can be thought of as finding the volume under a surface in three-dimensional space.

2. How is a double integral solved?

A double integral can be solved using various methods, such as the rectangular or polar coordinate systems, or by using the fundamental theorem of calculus. In some cases, it may also be solved using numerical methods.

3. What is a hypergeometric function?

A hypergeometric function is a special type of mathematical function that arises in the solution of certain differential equations. It is defined as a power series in which the coefficients satisfy a specific recursive relation.

4. How is a hypergeometric function used in solving double integrals?

In some cases, a double integral can be solved using a hypergeometric function as part of the solution process. This is because the hypergeometric function can be used to express certain types of integrals in a simpler form, making them easier to solve.

5. What are the applications of double integrals in science?

Double integrals have a wide range of applications in science, including in physics, engineering, economics, and statistics. They are used to calculate quantities such as area, volume, mass, and moment of inertia, and can also be used to model and solve various real-world problems.

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