Journal of the Mathematical Society of Japan

Examples of the Hurwitz transform

Masahiro HASHIMOTO, Shigeru KANEMITSU, and Hai-Long LI

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Espinosa and Moll [2], [3] studied “the Hurwitz transform” meaning an integral over [0, 1] of a Fourier series multiplied by the Hurwitz zeta function $\zeta (z,u)$, and obtained numerous results for those which arise from the Hurwitz formula. Ito's recent result [4] turns out to be one of the special cases of Espinosa and Moll's theorem. However, they did not give rigorous treatment of the relevant improper integrals.

In this note we shall appeal to a deeper result of Mikolás [9] concerning the integral of the product of two Hurwitz zeta functions and derive all important results of Espinosa and Moll. More importantly, we shall record the hidden and often overlooked fact that some novel-looking results are often the result of “duplicate use of the functional equation”, which ends up with a disguised form of the original, as in the case of Johnson's formula [5]. Typically, Example 9.1 ((1.12) below) is the result of a triplicate use because it depends not only on our Theorem 1, which is the result of a duplicate use, but also on (1.3), the functional equation itself.

Article information

J. Math. Soc. Japan Volume 61, Number 3 (2009), 651-660.

First available in Project Euclid: 30 July 2009

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Zentralblatt MATH identifier

Primary: 11M35: Hurwitz and Lerch zeta functions 33B15: Gamma, beta and polygamma functions

Hurwitz transform Hurwitz zeta function Lerch zeta function Hurwitz formula Lerch formula Clausen function Mikolás' result


LI, Hai-Long; HASHIMOTO, Masahiro; KANEMITSU, Shigeru. Examples of the Hurwitz transform. J. Math. Soc. Japan 61 (2009), no. 3, 651--660. doi:10.2969/jmsj/06130651.

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