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Vardi's Integral

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Vardi's integral is the beautiful definite integral

int_(pi/4)^(pi/2)lnlntanxdx=pi/2ln[sqrt(2pi)(Gamma(3/4))/(Gamma(1/4))]
(1)
=pi/4ln[(4pi^3)/(Gamma^4(1/4))]
(2)
=-0.2604428063009...
(3)

(OEIS A115252; Gradshteyn and Ryzhik 1980, p. 532; Moll 2006; Bailey et al. 2007, p. 160), where Gamma(z) is the gamma function.

Related definite integrals include

int_0^1lnln(1/x)(dx)/(1+x+x^2)=pi/(sqrt(3))ln[(2pi^(5/6))/(Gamma(1/6))]
(4)
int_0^1lnln(1/x)(dx)/(1-x+x^2)=pi/(3sqrt(3))ln[(32pi^5)/(Gamma^6(1/6))]
(5)

(Gradshteyn and Ryzhik 1980, pp. 571-572; Vardi 1988, Medina and Moll 2009).

See also

Definite Integral

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References

Bailey, D. H.; Borwein, J. M.; Calkin, N. J.; Girgensohn, R.; Luke, D. R.; and Moll, V. H. Experimental Mathematics in Action. Wellesley, MA: A K Peters, 2007.Bierens de Haan, D. Nouvelles Tables d'intégrales définies. Amsterdam, Netherlands, 1867.Gradshteyn, I. S. and Ryzhik, I. M. Tables of Integrals, Series, and Products, 4th ed. San Diego, CA: Academic Press, 1980.Medina, L. A. and Moll, V. H. "A Class of Logarithmic Integrals." Ramanujan J. 20, 91-126, 2009. https://doi.org/10.1007/s11139-008-9148-7.Moll, V. H. "Some Questions in the Evaluation of Definite Integrals." MAA Short Course, San Antonio, TX. Jan. 2006. https://www.experimentalmath.info/maa-course/Moll-MAA.pdf.Sloane, N. J. A. Sequence A115252 in "The On-Line Encyclopedia of Integer Sequences."Vardi, I. "Integrals, an Introduction to Analytic Number Theory." Amer. Math. Monthly 95, 308-315, 1988.

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Vardi's Integral

Cite this as:

Weisstein, Eric W. "Vardi's Integral." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/VardisIntegral.html

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