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A Generalization of Epstein Zeta Functions
Published online by Cambridge University Press: 20 November 2018
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§ 1. An Epstein zeta function (in its simplest form) is a function represented by the Dirichlet's series where a1… ak are real and n1, n2, … nk run through integral values. The properties of this function are well known and the simplest of them were proved by Epstein [2, 3]. The aim of this note is to define a general class of Dirichlet's series, of which the above can be viewed as an instance, and to discuss the problem of analytic continuation of such series.
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- Copyright © Canadian Mathematical Society 1949
References
1 Each eigenvalue being repeated according to its multiplicity and the eigenfunctions being real.
2 Though the Green's functions are different in the two boundary problems we use the same notation G(x, y; t) and there need be no confusion.
3 The iterated Green's function of Δu will belong to L2 for a sufficiently high order of iteration, from which it will follow that
is convergent if a is large and
will be absolutely convergent for large σ.
4 This series for the two dimensional domain was first studied by T. Carleman [1].
5 The author is indebted to Professor H. Weyl for this remark.
6 For a detailed discussion of these inequalities and the determination of the Green's function of the heat equation by Neumann's series cf. E. E. Levi [4, pp. 261-262.] We derive the inequality (21) assuming cos(rn) = 0(r) for small r. Similar inequalities can also be derived with cos (rn) = 0(ra) 0 < a ≤ 1 which is a regularity condition on B.
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