Abstract
We study analytic properties of the Tornheim zeta function \({\mathcal W}(r,s,t)\), which is also named after Mordell and Witten. In particular, we evaluate the function \({\mathcal W}(s,s,\tau s)\) (\(\tau >0\)) at \(s=0\) and, as our main result, find the derivative of this function at \(s=0\). Our principal tool is an identity due to Crandall that involves a free parameter and provides an analytic continuation. Furthermore, we derive special values of a permutation sum. Throughout this paper, we show by way of examples that Crandall’s identity can be used for efficient and high-precision evaluations of the Tornheim zeta function.
Similar content being viewed by others
References
Agoh, T., Dilcher, K.: Integrals of products of Bernoulli polynomials. J. Math. Anal. Appl. 381(1), 10–16 (2011)
Abramowitz, M., Stegun, I.A.: Handbook of Mathematical Functions. National Bureau of Standards, Washington, DC (1964)
Bailey, D.H., Borwein, J.M.: Computation and theory of Mordell–Tornheim–Witten sums II. J. Approx. Theory 197, 115–140 (2015)
Bailey, D.H., Borwein, J.M.: Computation and structure of character polylogarithms with applications to character Mordell–Tornheim–Witten sums. Math. Comput. 85(297), 295–324 (2016)
Bailey, D.H., Borwein, J.M.: Computation and experimental evaluation of Mordell–Tornheim–Witten sum derivatives. Exp. Math. (to appear)
Borwein, J.M.: Hilbert’s inequality and Witten’s zeta-function. Am. Math. Monthly 115(2), 125–137 (2008)
Borwein, J.M., Bailey, D.H.: Mathematics by Experiment. Plausible Reasoning in the 21st Century, 2nd edn. A K Peters Ltd., Wellesley (2008)
Borwein, J.M., Dilcher, K.: Analytic continuation and derivatives of character Mordell–Tornheim–Witten sums (in preparation)
Borwein, J.M., Dilcher, K., Tomkins, H.: The behaviour at the origin of multiple Witten zeta functions (in preparation)
Borwein, J.M., Zucker, I.J., Boersma, J.: The evaluation of character Euler double sums. Ramanujan J. 15, 377–405 (2008)
Carlitz, L.: Note on the integral of the product of several Bernoulli polynomials. J. Lond. Math. Soc. 34, 361–363 (1959)
Crandall, R.E.: Unified algorithms for polylogarithm, L-series, and zeta variants. In: Algorithmic Reflections: Selected Works. PSI Press, Portland (2012)
Crandall, R.E., Buhler, J.P.: On the evaluation of Euler sums. Exp. Math. 3(4), 275–285 (1995)
Dilcher, K.: A nonlinear identity of Bernoulli polynomials (2016). (Preprint)
Erdélyi, A., Magnus, W., Oberhettinger, F., Tricomi, F.G.: Higher Transcendental Functions, Vol. I. Based, in part, on notes left by Harry Bateman. McGraw-Hill, New York (1953)
Espinosa, O., Moll, V.H.: The evaluation of Tornheim double sums. I. J. Number Theory 116(1), 200–229 (2006)
Gradshteyn, I.S., Ryzhik, I.M.: Table of Integrals, Series, and Products, 7th edn. Elsevier/Academic Press, Amsterdam (2007)
Kurokawa, N., Ochiai, H.: Zeros of Witten zeta functions and absolute limit. Kodai Math. J. 36(3), 440–454 (2013)
Matsumoto, K.: On the analytic continuation of various multiple zeta-functions. In: Number Theory for the Millennium, II (Urbana: pp. 417–440, 2000). A K Peters, Natick (2002)
Mordell, L.J.: On the evaluation of some multiple series. J. Lond. Math. Soc. 33, 368–371 (1958)
Olver, F.W.J. (ed.): NIST Handbook of Mathematical Functions. Cambridge University Press, New York (2010)
Onodera, K.: Mordell–Tornheim multiple zeta values at non-positive integers. Ramanujan J. 32(2), 221–226 (2013)
Onodera, K.: A functional relation for Tornheim’s double zeta functions. Acta Arith. 162(4), 337–354 (2014)
Romik, D.: On the number of \(n\)-dimensional representations of \(SU(3)\), the Bernoulli numbers, and the Witten zeta function (2015)
Subbarao, M.V., Sitaramachandra, R.: Rao, On some infinite series of L. J. Mordell and their analogues. Pac. J. Math. 119(1), 245–255 (1985)
Tomkins, H.: An exploration of multiple zeta functions. Honours Thesis, Dalhousie University (2016)
Tornheim, L.: Harmonic double series. Am. J. Math. 72, 303–314 (1950)
Acknowledgements
We dedicate this paper to the memory of Richard E. Crandall (1947–2012), without whose insights and inspiration this work would not have been possible. We also thank Hayley Tomkins for helpful comments which led to an improved exposition. Finally, we thank one of the referees for bringing the papers [18], [22], and [23] to our attention.
Author information
Authors and Affiliations
Corresponding author
Additional information
J. M. Borwein passed away on Aug. 2, 2016, while this paper was under review. Research supported in part by the Natural Sciences and Engineering Research Council of Canada.
Rights and permissions
About this article
Cite this article
Borwein, J.M., Dilcher, K. Derivatives and fast evaluation of the Tornheim zeta function. Ramanujan J 45, 413–432 (2018). https://doi.org/10.1007/s11139-017-9890-9
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11139-017-9890-9
Keywords
- Tornheim zeta function
- Mordell–Tornheim double series
- Incomplete gamma function
- Polylogarithm
- Bernoulli polynomials