9

Question

How to evaluate

$$ \int_0^1 \frac{\ln(1-x) \ln^2 x \ln^2(1+x)}{1-x} \, dx $$

My attempt

To evaluate the integral

$$ I = \int_0^1 \frac{\ln(1-x) \ln^2 x \ln^2(1+x)}{1-x} \, dx $$

We can use a substitution to help simplify the integral. Let’s substitute $x = 1 - u $ Then, $dx = -du$, and the limits change as follows:

  • When $x = 0$, $u = 1$.
  • When $x = 1$, $u = 0$.

Thus, the integral transforms as follows:

$$ I = \int_1^0 \frac{\ln(1 - (1-u)) \ln^2(1-u) \ln^2(1 + (1-u))}{1 - (1-u)} (-du). $$

This simplifies to:

$$ I = \int_0^1 \frac{\ln(u) \ln^2(1-u) \ln^2(2-u)}{u} \, du. $$

I don't know the closed form of the integral; I got inspired by related integrals from the site.

Closed form $$-\frac{4}{3} \pi ^2 \text{Li}_4\left(\frac{1}{2}\right)+\frac{131 \zeta (3)^2}{16}+\frac{7}{3} \zeta (3) \ln ^3(2)-\frac{77}{24} \pi ^2 \zeta (3) \ln (2)+\frac{217}{8} \zeta (5) \ln (2)+\frac{41 \pi ^6}{30240}-\frac{1}{18} \pi ^2 \log ^4(2)-\frac{1}{144} \pi ^4 \log ^2(2)$$

Thanks to Mariusz Iwaniuk for the closed form.

  • Did you "invent" this problem ? – Claude Leibovici Oct 06 '24 at 04:37
  • @ClaudeLeibovici Probably yes, because I don't know if the problem is known in the literature. – Martin.s Oct 06 '24 at 04:45
  • 1
    The integral $I$ is called a weight 6 logarithmic integral. You can check out this paper for solution techniques. In fact, your integral has a polylogarithmic closed form given in that same article. – Nikitan Oct 06 '24 at 09:47
  • 2
    Mathematica with Package: MultipleZetaValues gives: $$-\frac{4}{3} \pi ^2 \text{Li}_4\left(\frac{1}{2}\right)+\frac{131 \zeta (3)^2}{16}+\frac{7}{3} \zeta (3) \ln ^3(2)-\frac{77}{24} \pi ^2 \zeta (3) \ln (2)+\frac{217}{8} \zeta (5) \ln (2)+\frac{41 \pi ^6}{30240}-\frac{1}{18} \pi ^2 \log ^4(2)-\frac{1}{144} \pi ^4 \log ^2(2)$$ – Mariusz Iwaniuk Oct 06 '24 at 09:58

2 Answers2

14

This is going to be strange, $$I=\int_0^1 \frac{\ln(1-x) \ln^2 (x) \ln^2(1+x)}{1-x} \, dx$$


Performing $\frac{1-x}{1+x}=u$,

$$I = \int_{0}^{1} \frac{\log\left(\frac{2u}{1+u}\right) \log^2\left(\frac{1-u}{1+u}\right) \log^2\left(\frac{2}{1+u}\right)}{u(1+u)} \, du$$

Using,

$$\log\left(\frac{2u}{1+u}\right) = \log 2 - \log u - \log(1+u)\tag1$$ $$\log^2\left(\frac{1-u}{1+u}\right) = \log^2(1-u) + \log^2(1+u)-2\log(1-u)\log(1+u)\tag2$$ $$\log^2\left(\frac{2}{1+u}\right) = \log^2 2 + \log^2(1+u)-2\log(2)\log(1+u)\tag3$$

Also,

$$\frac{1}{u(1+u)}=\frac{1}{u}-\frac{1}{1+u}$$

$$I = \int_{0}^{1} \frac{\log\left(\frac{2u}{1+u}\right) \log^2\left(\frac{1-u}{1+u}\right) \log^2\left(\frac{2}{1+u}\right)}{u} \, du-\int_{0}^{1} \frac{\log\left(\frac{2u}{1+u}\right) \log^2\left(\frac{1-u}{1+u}\right) \log^2\left(\frac{2}{1+u}\right)}{1+u} \, du$$

$$I = I_1-I_2$$

Section - 1

Working with our first integral,

$$I_1= \int_{0}^{1} \frac{\log\left(\frac{2u}{1+u}\right) \log^2\left(\frac{1-u}{1+u}\right) \log^2\left(\frac{2}{1+u}\right)}{u} \, du$$

Now after multiplying $(1),(2),(3)$,

$$\log^3(2)\log^2(1-u)+\log^3(2)\log^2(1+u)-2\log^3(2)\log(1-u)\log(1+u)-\log^2(2)\log(u)\log^2(1-u)-\log^2(2)\log(u)\log^2(1+u)+2\log^2(2)\log(u)\log(1-u)\log(1+u)-\log^2(2)\log(1+u)\log^2(1-u)-\log^2(2)\log^3(1+u)-2\log^2(2)\log(1-u)\log^2(1+u)+\log(2)\log^2(1-u)\log^2(1+u)+\log(2)\log^4(1+u)-2\log(2)\log(1-u)\log^3(1+u)-\log(u)\log^2(1-u)\log^2(1+u)-\log(u)\log^4(1+u)+2\log(u)\log(1-u)\log^3(1+u)-\log^3(1+u)\log^2(1-u)-\log^5(1+u)-2\log(1-u)\log^4(1+u)-2\log^2(2)\log(1+u)\log^2(1-u)-2\log^2(2)\log^2(1+u)+4\log^2(2)\log(1-u)\log^2(1+u)+2\log(2)\log(u)\log(1+u)\log^2(1-u)+2\log(2)\log(u)\log^3(1+u)-4\log(2)\log(u)\log(1-u)\log^2(1+u)+2\log(2)\log^2(1+u)\log^2(1-u)+2\log(2)\log^4(1+u)+4\log(2)\log(1-u)\log^3(1+u)$$

Dividing by $u$,

$$\frac{\log^3(2)\log^2(1-u)}{u}+\frac{\log^3(2)\log^2(1+u)}{u}-\frac{2\log^3(2)\log(1-u)\log(1+u)}{u}-\frac{\log^2(2)\log(u)\log^2(1-u)}{u}-\frac{\log^2(2)\log(u)\log^2(1+u)}{u}+\frac{2\log^2(2)\log(u)\log(1-u)\log(1+u)}{u}-\frac{\log^2(2)\log(1+u)\log^2(1-u)}{u}-\frac{\log^2(2)\log^3(1+u)}{u}-\frac{2\log^2(2)\log(1-u)\log^2(1+u)}{u}+\frac{\log(2)\log^2(1-u)\log^2(1+u)}{u}+\frac{\log(2)\log^4(1+u)}{u}-\frac{2\log(2)\log(1-u)\log^3(1+u)}{u}-\frac{\log(u)\log^2(1-u)\log^2(1+u)}{u}-\frac{\log(u)\log^4(1+u)}{u}+\frac{2\log(u)\log(1-u)\log^3(1+u)}{u}-\frac{\log^3(1+u)\log^2(1-u)}{u}-\frac{\log^5(1+u)}{u}-\frac{2\log(1-u)\log^4(1+u)}{u}-\frac{2\log^2(2)\log(1+u)\log^2(1-u)}{u}-\frac{2\log^2(2)\log^2(1+u)}{u}+\frac{4\log^2(2)\log(1-u)\log^2(1+u)}{u}+\frac{2\log(2)\log(u)\log(1+u)\log^2(1-u)}{u}+\frac{2\log(2)\log(u)\log^3(1+u)}{u}-\frac{4\log(2)\log(u)\log(1-u)\log^2(1+u)}{u}+\frac{2\log(2)\log^2(1+u)\log^2(1-u)}{u}+\frac{2\log(2)\log^4(1+u)}{u}+\frac{4\log(2)\log(1-u)\log^3(1+u)}{u}$$

We have,

$$I_1=\log^3(2)A+\log^3(2)B-2\log^3(2)C-D-\log^2(2)E+2\log^2(2)F-\log^2(2)G-H-2\log^2(2)K+\log(2)L+\log(2)M-2\log(2)N-P-Q+2R-S-T-2W-2\log^2(2)X-2\log^2(2)Y+4\log^2(2)Z+2\log(2)\alpha+2\log(2)\beta-4\log(2)\gamma+2\log(2)\delta+2\log(2)\Omega+4\log(2)\tau$$

Where, $$\boxed{A=\int_0^1 \frac{\log^2(1-u)}{u} \, du=2\zeta(3)}$$ solution of A

$$\boxed{B=\int_0^1 \frac{\log^2(1+u)}{u} \, du=\frac{1}{4}\zeta(3)}$$ solution of B

$$\boxed{C=\int_0^1 \frac{\log(1-u)\log(1+u)}{u} \, du=-\frac{5}{8}\zeta(3)}$$ solution of C

$$\boxed{D=\int_0^1 \frac{\log(u)\log^2(1-u)}{u} \, du=-\frac12 \zeta(4)}$$ solution of D

$$\boxed{E=\int_0^1 \frac{\log(u)\log^2(1+u)}{u} \, du=\frac{\pi^4}{24}-4\text{Li}_4 \left(\frac{1}{2} \right)-\frac{7\zeta(3)\ln 2}{2}+\frac{\pi^2\ln^2 2}{6}-\frac{\ln^4 2}{6}}$$ solution of E

$$\boxed{F=\int_0^1 \frac{\log(u)\log(1-u)\log(1+u)}{u} \, du=-\frac{3 \pi^4}{160}+\frac{7\log(2)}{4}\zeta(3)-\frac{\pi^2 \log^2(2)}{12} +\frac{\log^4(2)}{12}\quad+ 2 \text{Li}_4 \left(\frac{1}{2} \right)}$$ solution of F

$$\boxed{G=\int_0^1 \frac{\log^2(1-u)\log(1+u)}{u} \, du=2\operatorname{Li}_4\left(\frac{1}{2}\right)-\frac58\zeta(4)+\frac72\ln(2)\zeta(3)-\frac12\ln^2(2)\zeta(2)+\frac{1}{12}\ln^4(2)}$$ G was self-computed

$$\boxed{H=\int_0^1 \frac{\log^3(1+u)}{u} \, du=6\zeta(4)-\frac{21}{4}\ln(2)\zeta(3)+\frac{3}{2}\ln^{2}(2)\zeta(2)-\frac{1}{4}\ln^{4}(2)-6\operatorname{Li}_4\left(\frac{1}{2}\right)}$$ H was self-computed

$$\boxed{K=\int_0^1 \frac{\log(1-u)\log^2(1+u)}{u} \, du=-\frac {\pi^4}{240}}$$ solution of K

$$\boxed{L=\int_0^1 \frac{\log^2(1-u)\log^2(1+u)}{u} \, du=\frac{21}{24}\zeta(5)-\frac16\left(24\zeta(5)-\frac{21}{2}\ln^2(2)\zeta(3)+4\ln^3(2)\zeta(3)-\frac45\ln^5(2)-24\ln(2)\operatorname{Li}_4\left(\frac12\right)-24\operatorname{Li}_5\left(\frac12\right)\right)}$$ L was self-computed

$$\boxed{M=\int_0^1 \frac{\log^4(1+u)}{u}du=24\zeta(5)-\frac{21}{2}\ln^{2}(2)\zeta(3)+4\ln^{3}(2)\zeta(2)-\frac{4}{5}\ln^{5}(2)-24\ln(2)\operatorname{Li}_4\left(\frac{1}{2}\right)-24\operatorname{Li}_5\left(\frac{1}{2}\right)}$$ M was self-computed

$$\boxed{N=\int_0^1 \frac{\log(1-u)\log^3(1+u)}{u} \, du=-6\operatorname{Li}_5\left(\frac12\right)-6\ln2\operatorname{Li}_4\left(\frac12\right)+\frac{3}{4}\zeta(5)+\frac{21}{8}\zeta(2)\zeta(3)\\\quad-\frac{21}8\ln^22\zeta(3)+\ln^32\zeta(2)-\frac15\ln^52}$$

Solution of N

$$\boxed{P=\int_0^1 \frac{\log(u)\log^2(1+u)\log^2(1-u)}{u} \, du=-2 \zeta(\bar5,1)+8 \text{Li}_6\left(\frac{1}{2}\right)+4 \text{Li}_4\left(\frac{1}{2}\right) \log ^2(2)+8 \text{Li}_5\left(\frac{1}{2}\right) \log (2)-\frac{13 \zeta (3)^2}{16}+\frac{7}{6} \zeta (3) \log ^3(2)-\frac{221 \pi ^6}{30240}+\frac{\log ^6(2)}{9}-\frac{1}{12} \pi ^2 \log ^4(2)}$$ Solution of P


$$Q=\int_0^1 \frac{\log(u)\log^4(1+u)}{u} \, du$$

from here,

$$\mathcal{J}_{2}^{(4,1)} = - \frac{[\log(\tfrac{1}{2})]^{6}}{6}=-\frac16\log^6(2)$$

$$\mathcal{J}_{1}^{(4,1)}=-24\left[\zeta(6) - \operatorname{Li}_6\left(\frac12\right)-\log(2)\operatorname{Li}_5\left(\frac12\right)-\frac12\log^2(2)\operatorname{Li}_4\left(\frac12\right)-\frac16\log^3(2)\operatorname{Li}_3\left(\frac12\right)-\frac1{24}\log^4(2)\operatorname{Li}_2\left(\frac12\right) \right]$$

$$\mathcal{J}_{0}^{(4,1)} =-12 \left[ \zeta(5,1) - \zeta_1(2; 5, 1) - \log(2) \zeta_1(2; 4, 1) - \frac12\log^2(2) \zeta_1(2; 3, 1) - \frac16 \log^3(2) \zeta_1(2; 2, 1) \right]$$

Substituting these we can (possibly) obtain a closed form!

Alternatively,

Here's a partial proof to finding it's closed form;

Substitute $x=\frac{1-x}{x}$,

$$Q=\int_{\frac12}^1\frac{\ln(1-x)\ln^4(x)}{x(1-x)}\,dx-\int_{\frac12}^1\frac{\ln^5(x)}{x(1-x)}\,dx$$

We apply partial fractions to obtain 4 more integrals,

$$Q=\int_{\frac12}^1\frac{\ln(1-x)\ln^4(x)}{x}\,dx+\int_{\frac12}^1\frac{\ln(1-x)\ln^4(x)}{1-x}\,dx-\int_{\frac12}^1\frac{\ln^5(x)}{x}\,dx-\int_{\frac12}^1\frac{\ln^5(x)}{1-x}\,dx$$

While I'm not able to move on with the first two integrals, the last two are quite straightforward;

$$\int_{\frac12}^1\frac{\ln^5(x)}{x}\,dx=-\frac{\ln^6(2)}{6}$$

$$\int_{\frac12}^1\frac{\ln^5(x)}{1-x}\,dx=\sum_{n\ge 1} \int_{\frac12}^1 x^{n-1}\ln^5(x)\,dx$$

$$=\sum_{n\ge 1} \frac{\ln^5(2)}{n2^n}+\frac{5\ln^4(2)}{n^22^n}+\frac{20\ln^3(2)}{n^32^n}+\frac{60\ln^2(2)}{n^42^n}+\frac{120\ln(2)}{n^52^n}+\frac{120}{n^62^n}-\frac{120}{n^6}=120\,\operatorname{Li}_6\left(\tfrac{1}{2}\right) + 60\,\operatorname{Li}_4\left(\tfrac{1}{2}\right)\log^2(2) + 120\,\operatorname{Li}_5\left(\tfrac{1}{2}\right)\log(2) + \tfrac{35}{2}\zeta(3)\log^3(2) - \tfrac{8\pi^6}{63} + \tfrac{11\log^6(2)}{6} - \tfrac{5}{4}\pi^2\log^4(2)$$

All these sums are well known, I am not going to provide the proof for each,

You can compare the results integral and sum


$$R=\int_0^1 \frac{\log(u)\log(1-u)\log^3(1+u)}{u} \, du$$ $$S=\int_0^1 \frac{\log^3(1+u)\log^2(1-u)}{u} \, du$$

$$\boxed{T=\int_0^1 \frac{\log^5(1+u)}{u} \, du=\frac{1}{6}\ln^6(2)+\frac{8\pi^6}{63}+\sum_{n=0}^5 \binom{5}{n}\operatorname{Li}_{n+1}\left(\frac12\right)\ln^{5-n}(2)n!}$$ T was self-computed

$$W=\int_0^1 \frac{\log(1-u)\log^4(1+u)}{u} \, du$$

$$\boxed{X=\int_0^1 \frac{\log(1+u)\log^2(1-u)}{u} \, du=2\operatorname{Li}_4\left(\frac{1}{2}\right)-\frac58\zeta(4)+\frac72\ln(2)\zeta(3)-\frac12\ln^2(2)\zeta(2)+\frac{1}{12}\ln^4(2)}$$ Computed same as $G$

$$\boxed{Y=\int_0^1 \frac{\log^2(1+u)}{u} \, du=\frac{1}{4}\zeta(3)}$$ Above integral computed same as $B$

$$\boxed{Z=\int_0^1 \frac{\log^2(1+u)\log(1-u)}{u} \, du=-\frac {\pi^4}{240}}$$ Above integral computed same as $K$

$$\alpha=\int_0^1 \frac{\log(u)\log(1+u)\log^2(1-u)}{u} \, du$$

$$\boxed{\beta=\int_0^1 \frac{\log(u)\log^3(1+u)}{u} \, du=\frac{\pi^2}3\ln^32-\frac25\ln^52+\frac{\pi^2}2\zeta(3)+\frac{99}{16}\zeta(5)-\frac{21}4\zeta(3)\ln^22\\-12\operatorname{Li}_4\left(\frac12\right)\ln2-12\operatorname{Li}_5\left(\frac12\right)}$$ Solution of the above integral

$$\boxed{\gamma=\int_0^1 \frac{\log(u)\log(1-u)\log^2(1+u)}{u} \, du=\frac{7\pi^2}{48}\zeta(3)-\frac{25}{16}\zeta(5)}$$ Solution of the above integral

$$\boxed{\delta=\int_0^1 \frac{\log^2(1-u)\log^2(1+u)}{u} \, du=\frac{21}{24}\zeta(5)-\frac16\left(24\zeta(5)-\frac{21}{2}\ln^2(2)\zeta(3)+4\ln^3(2)\zeta(3)-\frac45\ln^5(2)-24\ln(2)\operatorname{Li}_4\left(\frac12\right)-24\operatorname{Li}_5\left(\frac12\right)\right)}$$ Above integral computed same as $L$

$$\boxed{\Omega=\int_0^1 \frac{\log^4(1+u)}{u} \, du=24\zeta(5)-\frac{21}{2}\ln^{2}(2)\zeta(3)+4\ln^{3}(2)\zeta(2)-\frac{4}{5}\ln^{5}(2)-24\ln(2)\operatorname{Li}_4\left(\frac{1}{2}\right)-24\operatorname{Li}_5\left(\frac{1}{2}\right)} $$ $\Omega$ was self-computed

$$\boxed{\tau=\int_0^1 \frac{\log(1-u)\log^3(1+u)}{u} \, du=-6\operatorname{Li}_5\left(\frac12\right)-6\ln2\operatorname{Li}_4\left(\frac12\right)+\frac{3}{4}\zeta(5)+\frac{21}{8}\zeta(2)\zeta(3)\\\quad-\frac{21}8\ln^22\zeta(3)+\ln^32\zeta(2)-\frac15\ln^52}$$

Above integral is computed same as $N$

Section - 2

Working with our second integral,

$$I_2= \int_{0}^{1} \frac{\log\left(\frac{2u}{1+u}\right) \log^2\left(\frac{1-u}{1+u}\right) \log^2\left(\frac{2}{1+u}\right)}{1+u} \, du$$

Now after multiplying $(1),(2),(3)$,

$$\log^3(2)\log^2(1-u)+\log^3(2)\log^2(1+u)-2\log^3(2)\log(1-u)\log(1+u)-\log^2(2)\log(u)\log^2(1-u)-\log^2(2)\log(u)\log^2(1+u)+2\log^2(2)\log(u)\log(1-u)\log(1+u)-\log^2(2)\log(1+u)\log^2(1-u)-\log^2(2)\log^3(1+u)-2\log^2(2)\log(1-u)\log^2(1+u)+\log(2)\log^2(1-u)\log^2(1+u)+\log(2)\log^4(1+u)-2\log(2)\log(1-u)\log^3(1+u)-\log(u)\log^2(1-u)\log^2(1+u)-\log(u)\log^4(1+u)+2\log(u)\log(1-u)\log^3(1+u)-\log^3(1+u)\log^2(1-u)-\log^5(1+u)-2\log(1-u)\log^4(1+u)-2\log^2(2)\log(1+u)\log^2(1-u)-2\log^2(2)\log^2(1+u)+4\log^2(2)\log(1-u)\log^2(1+u)+2\log(2)\log(u)\log(1+u)\log^2(1-u)+2\log(2)\log(u)\log^3(1+u)-4\log(2)\log(u)\log(1-u)\log^2(1+u)+2\log(2)\log^2(1+u)\log^2(1-u)+2\log(2)\log^4(1+u)+4\log(2)\log(1-u)\log^3(1+u)$$

Dividing by $1+u$,

$$\frac{\log^3(2)\log^2(1-u)}{1+u}+\frac{\log^3(2)\log^2(1+u)}{1+u}-\frac{2\log^3(2)\log(1-u)\log(1+u)}{1+u}-\frac{\log^2(2)\log(u)\log^2(1-u)}{1+u}-\frac{\log^2(2)\log(u)\log^2(1+u)}{1+u}+\frac{2\log^2(2)\log(u)\log(1-u)\log(1+u)}{1+u}-\frac{\log^2(2)\log(1+u)\log^2(1-u)}{1+u}-\frac{\log^2(2)\log^3(1+u)}{1+u}-\frac{2\log^2(2)\log(1-u)\log^2(1+u)}{1+u}+\frac{\log(2)\log^2(1-u)\log^2(1+u)}{1+u}+\frac{\log(2)\log^4(1+u)}{1+u}-\frac{2\log(2)\log(1-u)\log^3(1+u)}{1+u}-\frac{\log(u)\log^2(1-u)\log^2(1+u)}{1+u}-\frac{\log(u)\log^4(1+u)}{1+u}+\frac{2\log(u)\log(1-u)\log^3(1+u)}{1+u}-\frac{\log^3(1+u)\log^2(1-u)}{1+u}-\frac{\log^5(1+u)}{1+u}-\frac{2\log(1-u)\log^4(1+u)}{1+u}-\frac{2\log^2(2)\log(1+u)\log^2(1-u)}{1+u}-\frac{2\log^2(2)\log^2(1+u)}{1+u}+\frac{4\log^2(2)\log(1-u)\log^2(1+u)}{1+u}+\frac{2\log(2)\log(u)\log(1+u)\log^2(1-u)}{1+u}+\frac{2\log(2)\log(u)\log^3(1+u)}{1+u}-\frac{4\log(2)\log(u)\log(1-u)\log^2(1+u)}{1+u}+\frac{2\log(2)\log^2(1+u)\log^2(1-u)}{1+u}+\frac{2\log(2)\log^4(1+u)}{1+u}+\frac{4\log(2)\log(1-u)\log^3(1+u)}{1+u}$$

We have,

$$I_1=\log^3(2)A+\log^3(2)B-2\log^3(2)C-D-\log^2(2)E+2\log^2(2)F-\log^2(2)G-H-2\log^2(2)K+\log(2)L+\log(2)M-2\log(2)N-P-Q+2R-S-T-2W-2\log^2(2)X-2\log^2(2)Y+4\log^2(2)Z+2\log(2)\alpha+2\log(2)\beta-4\log(2)\gamma+2\log(2)\delta+2\log(2)\Omega+4\log(2)\tau$$

Where,

Please note I am out of notations to use so Ill be reusing the old ones,

$$\boxed{A=\int_0^1 \frac{\log^2(1-u)}{1+u} \, du=\frac{7}{4}\zeta(3)+\frac13\ln^3(2)-\frac{\pi^2}{6}\ln(2)}$$ A was self-computed

$$\boxed{B=\int_0^1 \frac{\log^2(1+u)}{1+u} \, du=\frac13 \ln^3(2)}$$ B was self-computed

$$\boxed{C=\int_0^1 \frac{\log(1-u)\log(1+u)}{1+u} \, du = \frac{1}{3}\log^3(2)-\frac{\pi^2}{12}\log(2)+\frac{\zeta(3)}{8}}$$ Solution to C

$$\boxed{D=\int_0^1 \frac{\log(u)\log^2(1-u)}{1+u} \, du=\frac{11}{4}\zeta(4)-\frac14\ln^42-6\operatorname{Li}_4\left(\frac12\right)}$$ Solution to D

$$\boxed{E=\int_0^1 \frac{\log(u)\log^2(1+u)}{1+u} \, du=2 \, \text{Li}_4\left(\frac{1}{2}\right) + \frac{7}{4} \, \zeta(3) \ln(2) - \frac{\pi^4}{45} + \frac{\ln^4(2)}{12} - \frac{1}{12} \pi^2 \ln^2(2)} $$

E was self-computed

$$\boxed{F=\int_0^1 \frac{\log(u)\log(1-u)\log(1+u)}{1+u} \, du= 2\operatorname{Li}_4\left(\dfrac{1}{2}\right)+\dfrac{21}{8}\zeta(3)\ln 2 - \dfrac{1}{45}\pi^4 + \dfrac{1}{12}\ln^4 2 - \dfrac{5}{24}\pi^2\ln^2 2}$$ F was self-computed

$$\boxed{G=\int_0^1 \frac{\log^2(1-u)\log(1+u)}{1+u} \, du=-\frac{1}{4}\zeta \left(4\right)+2\ln \left(2\right)\zeta \left(3\right)-\ln ^2\left(2\right)\zeta \left(2\right)+\frac{1}{4}\ln ^4\left(2\right)}$$ Solution to G

$$\boxed{H=\int_0^1 \frac{\log^3(1+u)}{1+u} \, du=\frac14 \ln^4(2)}$$ H was self-computed

$$\boxed{K=\int_0^1 \frac{\log(1-u)\log^2(1+u)}{1+u} \, du=2\operatorname{Li}_4\left(\frac{1}{2}\right)+2\zeta(3)\log(2)+\frac13\log^4(2)-\frac{\pi^4}{45}-\frac{\pi^2}{6}\log^2(2)}$$ K was self-computed

$$\boxed{L=\int_0^1 \frac{\log^2(1-u)\log^2(1+u)}{1+u} \, du=-4\operatorname{Li}_5\left(\frac12\right)+4\zeta(3)\log^2(2)-\frac{2\pi^2}9 \log^3(2)-\frac{\pi^2}{3}\zeta(3)-\frac{\pi^4}{20}\log2+\frac7{30}\log^5(2)+ \frac{63}8\zeta(5) }$$ Solution to above integral

$$\boxed{M=\int_0^1 \frac{\log^4(1+u)}{1+u} \, du=\frac15 \ln^5(2)}$$ M was self-computed

$$\boxed{N=\int_0^1 \frac{\log(1-u)\log^3(1+u)}{1+u} \, du=6\zeta(5)-6\operatorname{Li}_5\left(\frac12\right)-\frac{\pi^4}{15}\ln(2)+3\ln^2(2)\zeta(3)-\frac{\pi^2}{6}\ln^3(2)+\frac14 \ln^5(2)}$$ Solution to N

$$P=\int_0^1 \frac{\log(u)\log^2(1+u)\log^2(1-u)}{1+u} \, du$$

$$\boxed{Q=\int_0^1 \frac{\log(u)\log^4(1+u)}{1+u} \, du=24\operatorname{Li}_6\left(\frac12\right)-\frac{8}{315}\pi^6-\frac{\pi^2}{4}\ln^4(2)+24\ln(2)\operatorname{Li}_5\left(\frac12\right)+12\ln^2(2)\operatorname{Li}_4\left(\frac12\right)+\frac{7}{2}\zeta(3)\ln^3(2)+\frac13\ln^6(2)}$$ Q was self-computed


$$R=\int_0^1 \frac{\log(u)\log(1-u)\log^3(1+u)}{1+u} \, du$$

Here's a partial proof :

$$ab^3=\frac{1}{8}(a+b)^4-\frac{1}{8}(a-b)^4-a^3b$$

$$R=\int _0^1\frac{\log (u)\log (1-u)\log ^3(1+u)}{1+u}du$$

$$a=\log(1-u), b=\log(1+u)$$

$$\implies\log(1-u)\log^3(1+u)=\frac{1}{8}\log^4(1-u^2)-\frac{1}{8}\log^4\left(\frac{1-u}{1+u}\right)-\log^3(1-u)\log(1+u)$$

$$R=\frac{1}{8}\int_0^1\frac{\log(u)\log^4(1-u^2)}{1+u}\,du-\frac{1}{8}\int_0^1\frac{\log(u)\log^4\left(\frac{1-u}{1+u}\right)}{1+u}\,du-\int_0^1\frac{\log(u)\log^3(1-u)\log(1+u)}{1+u}\,du$$

$$\int_0^1\frac{\log(u)\log^4(1-u^2)}{1+u}\,du=\int_0^1\frac{\log(u)\log^4(1-u^2)}{1-u^2}(1-u)\,du$$

$$u^2=t\implies \,du=\frac{1}{2\sqrt{t}}\,dt$$

$$\int_0^1\frac{\log(\sqrt{t})\log^4(1-t)}{1-t}\left(1-\sqrt{t}\right)\frac{1}{2\sqrt{t}}\,dt\implies\frac14\int_0^1\frac{\log(u)\log^4(1-u)}{\sqrt{t}(1-t)}-\frac14\int_0^1\frac{\log(u)\log^4(1-u)}{(1-t)}$$

The above two integrals can be evaluated using the Beta function (routine method)

$$\int_0^1\frac{\log(u)\log^4\left(\frac{1-u}{1+u}\right)}{1+u}\,du$$ $$\underset{\frac{1-u}{1+u}=t}{=}\int_0^1 \frac{\log(1 - t) \log^4(t)}{1 + t} \, dt-\int_0^1 \frac{\log(1 + t) \log^4(t)}{1 + t} \, dt$$

Need to work on the above two integrals....

$$\int_0^1 \frac{\log(u)\log(1+u)\log^3(1-u)}{1+u} \, du$$

We can follow a similar path as followed in calculating $\alpha$ from section 2.


$$\boxed{S=\int_0^1 \frac{\log^3(1+u)\log^2(1-u)}{1+u} \, du=-12 \text{Li}_6\left(\frac{1}{2}\right)-12 \text{Li}_5\left(\frac{1}{2}\right) \ln (2)+6 \zeta^2 (3)+8 \zeta (3) \ln ^3(2)-12 \zeta(2) \zeta (3) \ln (2)+36 \zeta (5) \ln (2)-9\zeta(6)+\frac{1}{4}\ln ^6(2)-2\zeta(2) \ln ^4(2)-\frac{27}{2} \zeta(4) \ln ^2(2)+12 \sum_{n=1}^\infty\frac{H_n}{n^52^n}}$$

S was self-computed, Also no closed form for that sum

$$\boxed{T=\int_0^1 \frac{\log^5(1+u)}{1+u} \, du=\frac16 \ln^6(2)}$$ T was self-computed

$$\boxed{W=\int_0^1 \frac{\log(1-u)\log^4(1+u)}{1+u} \, du=24\operatorname{Li}_6\left(\frac12\right)-\frac{8}{315}\pi^6+24\ln(2)\zeta(5)-\frac{2}{15}\pi^4\ln^2(2)+4\ln^3(2)\zeta(3)-\frac{\pi^2}{6}\ln^4(2)+\frac15\ln^5(2)}$$ Solution to W

$$\boxed{X=\int_0^1 \frac{\log(1+u)\log^2(1-u)}{1+u} \, du= 2 \zeta (3) \log (2)-\frac{\pi ^4}{360}+\frac{\log ^4(2)}{4}-\frac{1}{6} \pi ^2 \log ^2(2)}$$ Solution to X

$$\boxed{Y=\int_0^1 \frac{\log^2(1+u)}{1+u} \, du=\frac13 \ln^3(2)}$$ Y was self-computed

$$\boxed{Z=\int_0^1 \frac{\log^2(1+u)\log(1-u)}{1+u} \, du=2\operatorname{Li}_4\left(\frac{1}{2}\right)+2\zeta(3)\log(2)+\frac13\log^4(2)-\frac{\pi^4}{45}-\frac{\pi^2}{6}\log^2(2)}$$ Z was self-computed


$$\boxed{\alpha=\int_0^1 \frac{\log(u)\log(1+u)\log^2(1-u)}{1+u} \, du = \frac{21}{8}\log^2(2)\zeta(3)-\frac{15}{8}\log(2)\zeta(4)+\frac{121}{16}\zeta(5)-\frac23\log^3(2)\zeta(2)-\frac{1}{15}\log^5(2)-2\log(2)\operatorname{Li}_4\left(\frac12\right)-2\operatorname{Li}_5\left(\frac12\right)-3\zeta(2)\zeta(3)}$$

Proof : Here, we can re-write our integral as follows,

$$\int_0^1 \frac{\log(u)\log(1+u)\log^2(1-u)}{1+u} \, du=\frac{1}{6}\int_0^1\frac{(1-u)\log(u)\log^3(1-u^2)}{1-u^2}\,du-\frac{1}{6}\int_0^1\frac{(1-u)\log^3(u)\log(1-u^2)}{1-u^2}\,du+\frac13\int_0^1\frac{\log^3(u)\log(1+u)}{1+u}\,du-\frac13\int_0^1\frac{\log(u)\log^3(1+u)}{1+u}\,du$$

Apply IBP to the last two integrals and for first two make the substitution of $u^2\to u$, we can obtain known integrals in text.


$$\boxed{\beta=\int_0^1 \frac{\log(u)\log^3(1+u)}{1+u} \, du=6 \, \text{Li}_5\left(\frac{1}{2}\right) + 6\text{Li}_4\left(\frac{1}{2}\right) \ln(2) - 6 \, \zeta(5) + \frac{21}{8} \, \zeta(3) \ln^2(2) + \frac{\ln^5(2)}{5} - \frac{1}{6} \pi^2 \ln^3(2)}$$ $\beta$ was self-computed


$$\gamma=\int_0^1 \frac{\log(u)\log(1-u)\log^2(1+u)}{1+u} \, du$$

You can try the following for $a=1,b=1,c=2$,

$$\sin \pi (b-a) \int_0^1 x^{b-1}(1-x)^{c-b-1}(1+x)^{-a} dx = \sin \pi (c-a) \int_0^1 x^{a-c} \left[ (1-x)^{c-a-1}(1+x)^{-b} - 1 \right] dx - \sin \pi (b-a) \frac{\Gamma(c-b)\Gamma(b)}{\Gamma(a)\Gamma(c-a)} \int_0^1 x^{b-c} \left[ (1-x)^{c-a-1}(1+x)^{-b} - 1 \right] dx + \frac{\sin \pi (c-a)}{a-c+1} - \frac{\pi \Gamma(b)}{\Gamma(2-c+b)\Gamma(a)\Gamma(c-a)}$$

You will have to perform the below,

$$\frac{\partial}{\partial a^m \partial b^n \partial c^r}$$

Picking appropriate $m,n,r$


$$\boxed{\delta=\int_0^1 \frac{\log^2(1-u)\log^2(1+u)}{1+u} \, du=-4\operatorname{Li}_5\left(\frac12\right)+4\zeta(3)\log^2(2)-\frac{2\pi^2}9 \log^3(2)-\frac{\pi^2}{3}\zeta(3)-\frac{\pi^4}{20}\log2+\frac7{30}\log^5(2)+ \frac{63}8\zeta(5) }$$

Computed same as $L$

$$\boxed{\Omega=\int_0^1 \frac{\log^4(1+u)}{1+u} \, du=\frac15\ln^5(2)}$$ $\Omega$ was self-computed

$$\boxed{\tau=\int_0^1 \frac{\log(1-u)\log^3(1+u)}{1+u} \, du=6\zeta(5)-6\operatorname{Li}_5\left(\frac12\right)-\frac{\pi^4}{15}\ln(2)+3\ln^2(2)\zeta(3)-\frac{\pi^2}{6}\ln^3(2)+\frac14 \ln^5(2)}$$ Solution to above integral

All the above integrals are known and trivial, derived from the beta function, Not to mention all the "self-computed" and other related/similar integrals are well-documented in text and on/off this site as well

$$\int_0^1 t^{a-1}(1-t)^{b-1}\,dt=\beta(a,b)$$

$$\int_{-1}^1(1-t)^{a-1}(1+t)^{b-1}\,dt=2^{a+b-1}\beta(a,b)$$

$$\displaystyle \int_0^1 \frac{x^{a-1}+x^{b-1}}{(1+x)^{a+b}} \textrm{d}x = \beta(a,b)$$


Recap : We are still missing the closed form/proofs for the following integrals :

From section-1,

  • $R=\int_0^1 \frac{\log(u)\log(1-u)\log^3(1+u)}{u} \, du$

  • $S=\int_0^1 \frac{\log^3(1+u)\log^2(1-u)}{u} \, du$

  • $W=\int_0^1 \frac{\log(1-u)\log^4(1+u)}{u} \, du$

  • $Q=\int_0^1 \frac{\log(u)\log^4(1+u)}{u} \, du$, which also gave us two more $\int_{\frac12}^1\frac{\ln(1-x)\ln^4(x)}{x}\,dx$ and $\int_{\frac12}^1\frac{\ln(1-x)\ln^4(x)}{1-x}\,dx$, the other refernce does involve a generalized solution.

  • $\alpha=\int_0^1 \frac{\log(u)\log(1+u)\log^2(1-u)}{u} \, du$

From Section -2,

  • $P=\int_0^1 \frac{\log(u)\log^2(1+u)\log^2(1-u)}{1+u} \, du$

  • $R=\int_0^1 \frac{\log(u)\log(1-u)\log^3(1+u)}{1+u} \, du$, which also gave us three more $\int_0^1 \frac{\log(1 - t) \log^4(t)}{1 + t} \, dt$ and $\int_0^1 \frac{\log(1 + t) \log^4(t)}{1 + t} \, dt$ and $\int_0^1 \frac{\log(u)\log(1+u)\log^3(1-u)}{1+u} \, du$

  • $\gamma=\int_0^1 \frac{\log(u)\log(1-u)\log^2(1+u)}{1+u} \, du$


Another approach may go this way,

$$I=\int_0^1 \frac{\ln(1-x) \ln^2(1+x)\ln^2 x}{1-x} \, dx$$

Using the Identity,

$$ab^2=\frac{1}{6}(a+b)^3+\frac{1}{6}(a-b)^3-\frac{1}{3}a^3$$

Where,

$$a=\ln(1-x)\,||||\, b=\ln(1+x)$$

$$\ln(1-x)\ln^2(1+x)=\frac{1}{6}(\ln(1-x)+\ln(1+x))^3+\frac{1}{6}(\ln(1-x)-\ln(1+x))^3-\frac{1}{3}(\ln(1-x))^3$$

$$\ln(1-x)\ln^2(1+x)=\frac{1}{6}\ln^3(1-x^2)+\frac{1}{6}\ln^3\left(\frac{1-x}{1+x}\right)-\frac{1}{3}\ln^3(1-x)$$

$$\ln(1-x)\ln^2(1+x)\ln^2 x=\frac{1}{6}\ln^3(1-x^2)\ln^2 x+\frac{1}{6}\ln^3\left(\frac{1-x}{1+x}\right)\ln^2 x-\frac{1}{3}\ln^3(1-x)\ln^2 x$$

$$\frac{\ln(1-x)\ln^2(1+x)\ln^2 x}{1-x}=\frac{1}{6}\frac{\ln^3(1-x^2)\ln^2 x}{1-x}+\frac{1}{6}\frac{\ln^3\left(\frac{1-x}{1+x}\right)\ln^2 x}{1-x}-\frac{1}{3}\frac{\ln^3(1-x)\ln^2 x}{1-x}$$

$$I=\frac{1}{6}\int_0^1\frac{\ln^3(1-x^2)\ln^2 (x)}{1-x}\,dx+\frac{1}{6}\int_0^1\frac{\ln^3\left(\frac{1-x}{1+x}\right)\ln^2(x)}{1-x}\,dx-\frac{1}{3}\int_0^1\frac{\ln^3(1-x)\ln^2 (x)}{1-x}\,dx$$

You can then refer here and here and here for further.

Amrut Ayan
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  • 3
    +1) This is the kind of answer that I immediately bookmark. The links you've compiled to related integrals seem very handy to have in one place :) – David H Dec 21 '24 at 14:02
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    @DavidH thank you sir, there’s a lot more integrals in there to complete with proof/references, hopefully whenever I’m free I’ll keep editing – Amrut Ayan Dec 21 '24 at 14:27
3

Let's consider the general case

$$I(a,n)= \int_{0}^{1}x^a\ln^n (x)\frac{\ln(1-x) \ln^2(1+x)}{1-x} \, dx;\,n=0,1... $$

All we need is the following expansion:

$$\ln^2(1-x)=2\sum_{m=2}^{\infty}\frac{H_{m-1}}{m}x^m$$

where $$H_{m}=\sum_{k=1}^{m}\frac{1}{k}$$

Now differentiate the expansion with respect to $x$

$$\frac{\ln(1-x)}{1-x}=-\sum_{m=1}^{\infty}H_{m}x^m$$

In the original expansion, we take $-x$ instead of $x$

$$\ln^2(1+x)=2\sum_{m=2}^{\infty}(-1)^m\frac{H_{m-1}}{m}x^m$$

Now we form the product

$$x^a\frac{\ln(1-x) \ln^2(1+x)}{1-x}$$

and integrate $$\int_{0}^{1}x^a\frac{\ln(1-x) \ln^2(1+x)}{1-x} \, dx = $$

$$=-2\sum_{m=3}^{\infty}\frac{(-1)^mf(m)}{m+1+a}$$

where $$f(m)=\sum_{i=1}^{m-1}(-1)^i\frac{H_{i}H_{m-1-i}}{m-i}$$

Finally, we differentiate the obtained result by $a$ $n$ times and get the final result:

$$I(a,n)=-2(-1)^nn!\sum_{m=3}^{\infty}\frac{(-1)^mf(m)}{(m+1+a)^{n+1}}$$

We get the integral given in the original post here by taking $a=0$ and $n=2$

Martin Gales
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