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Questions related to various forms of integration including the Riemann integral, Lebesgue integral, Riemann–Stieltjes integral, double integrals, line integrals, contour integrals, surface integrals, integrals of differential forms, ...

25 votes
2 answers
2k views

Interesting integral

Numerical evidence shows the validity of the following identity $$\int\limits_0^z\frac{xdx}{\sin{x}\sqrt{\sin^2{z}-\sin^2{x}}}=\frac{\pi}{4\sin{z}}\ln{\frac{1+\sin{z}}{1-\sin{z}}},\tag{1}$$ if $0< z< …
Zurab Silagadze's user avatar
21 votes
0 answers
651 views

A multiple integral

Let us consider the multiple integral $$I_{n}=\int_{-\infty }^{\infty }ds_{1}\int_{-\infty}^{s_{1}}ds_{2}\cdots \int_{-\infty }^{s_{2n-1}}ds_{2n}\;\cos {(s_{1}^{2}-s_{2}^{2})}\;\cdots \cos {(s_{2n-1 …
Zurab Silagadze's user avatar
11 votes
Accepted

A closed form for an integral expressed as a finite series of $\zeta(2k+1)$, $\pi^m$ and a r...

I think the following articles can give a clue: http://www.tandfonline.com/doi/abs/10.1080/10652460701688125?journalCode=gitr20 (Closed-form evaluation of some families of cotangent and cosecant integ …
Zurab Silagadze's user avatar
11 votes
1 answer
451 views

Calculation of the integral related to the gravitational shock wave

They write that they "have not attempted to perform the integration explicitly". Was this integral ever calculated explicitly? …
Zurab Silagadze's user avatar
10 votes

volume over a hypercube, over simplex: twist by Euler numbers

This is only a partial answer. The Beukers-Kolk-Calabi change of variables $$x_1=\frac{\sin{u_1}}{\cos{u_2}},\;\;x_2=\frac{\sin{u_2}}{\cos{u_3}},\ldots, \;x_{n-1}=\frac{\sin{u_{n-1}}}{\cos{u_n}},\;\;x …
Zurab Silagadze's user avatar
8 votes
2 answers
942 views

Interesting triple integral

Some time ago I stumbled on an alleged identity $$\int\limits_0^\infty \frac{dx}{x} \int\limits_0^x \frac{dy}{y} \int\limits_0^y \frac{dz}{z} [\sin{x}+\sin{(x-y)}-\sin{(x-z)}-\sin{(x-y+z)}]= -\frac{\p …
Zurab Silagadze's user avatar
7 votes
Accepted

Legendre Polynomial Integral

The integral $$\int\limits_0^1 x^k P_m(x)P_n(x)dx$$ is evaluated in terms of the hypergeometric function $_3F_2$ in http://link.springer.com/article/10.1007/BF01650571 (Some integrals containing produ …
Zurab Silagadze's user avatar
7 votes
1 answer
561 views

Basel problem and inversive geometry

.$$ The integration domain in the last integral is determined by the conditions $0\le x,y\le 1$, which gives $$-\frac{\phi}{2}\le\theta\le\frac{\phi}{2},\;\;\;\phi-\frac{\pi}{2}\le\theta\le\frac{\pi}{ … \cos{\theta}},\;\;\;y=\frac{\sin{\theta}}{\cos{\phi}}.$$ Its Jacobian is $1-x^2y^2$ and it is applied to the integral $$\zeta(2)=\frac{4}{3}\int_0^1\int_0^1\frac{dx\,dy}{1-x^2y^2}.$$ In this case the integration
Zurab Silagadze's user avatar
7 votes
2 answers
2k views

The source of the Integral

Wolfram alpha calculates the integral $$\int\limits_0^\infty \frac{x^2\ln{x}}{e^x-1}dx=2\zeta^\prime(3)+3\zeta(3)-2\gamma\zeta(3).$$ However, I need to cite the source of this identity (the table of i …
Zurab Silagadze's user avatar
7 votes

Computing $\int_0^T e^{itA}Be^{-itA} dt$ without an infinite series

I hope the following article can help: http://iopscience.iop.org/1063-7869/50/12/A02;jsessionid=EB2515B1F7F6CB626A8CBEF4537BBE05.c1 (Feynman disentangling of noncommuting operators and group represent …
Zurab Silagadze's user avatar
6 votes
1 answer
708 views

Аrе thеsе integrals known?

While studying some dark matter related stuff, I came across to the following interesting identities: $$\int\limits_0^\infty\sqrt{\frac{y}{xp}}\,e^{-y}\left(K(p)-E(p)\right)dy= \frac{\pi x}{4} \left[I …
Zurab Silagadze's user avatar
6 votes
2 answers
308 views

Choice of branch cuts in logarithmic integral

According to 8.111 from Lewin's book "Polylogarithms and associated functions", it is expected that $$\int\limits_0^2\frac{\ln{(1-x)}\ln{(1+x)}}{x}\,dx=Li_3(-3)+\zeta(3)-2Li_3(3)+$$ $$\ln{3}\left[Li_2 …
Zurab Silagadze's user avatar
5 votes
1 answer
932 views

Identity involving Fresnel integrals

In the paper E. Mehlum, Appell and the apple (nonlinear splines in space), Technical Report No. 1676 (1981), Central institute for industrial research, Oslo (reproduced in the book Mathematical Method …
Zurab Silagadze's user avatar
5 votes

Is there a closed form of $\int_0^\frac12\dfrac{\text{arcsinh}^nx}{x^m}dx$?

The following results are quoted in http://www.hindawi.com/journals/ijmms/2007/019381/abs/ (Integer Powers of Arcsin, by J.M. Borwein and M. Chamberland): $$\large I(4,1)=-\frac{3}{2}\mathrm{Li}_5(g^2 …
Zurab Silagadze's user avatar
5 votes
Accepted

Generalizations of the Euler–Maclaurin Summation Formula

As for point (1), maybe the following references will be useful: The Euler–Maclaurin formula revisited, by D. Elliott The Euler–Maclaurin expansion and finite-part integrals, by G. Monegato, J.N. Ly …
Zurab Silagadze's user avatar

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