Preprint No. A-99-06

Rudolf Gorenflo, Ioulia Loutchko, Yuri Luchko

Numerische Berechnung der Mittag-Leffler-Funktion
Ealpha, beta(z) und ihrer Ableitung

Abstract: Recently it turned out that the role of the well-known {\sl Mittag-Leffler function} \[ E_{\alpha} (z) := \sum_{n=0}^{\infty} \frac{z^n}{\Gamma (\alpha n + 1)}, \ \alpha > 0, \ z\in {\bf C} \] and the {\sl generalized Mittag-Leffler function} \[ E_{\alpha,\beta} (z) := \sum_{n=0}^{\infty} \frac{z^n}{\Gamma (\alpha n + \beta)}, \ \alpha > 0, \ \beta \in {\bf C},\ z\in {\bf C} \] in different branches of analysis is more essential than it seemed before. Mainly these applications are due to connections of the Mittag-Leffler functions with fractional calculus. In this paper we first obtain a modification of the Dzherbasyan integral representation for the generalized Mittag-Leffler function. This representation and the series representations (for small values of the argument $z$) are then used for numerical evaluations of the Mittag-Leffler functions for all possible values of the parameters and arguments. The estimates of the errors of evaluations are given. A method for the numerical evaluation of the derivative of the generalized Mittag-Leffler function is considered.

Keywords: Mittag-Leffler function, integral representations, numerical evaluations

Mathematics Subject Classification (MSC91): 33E20 Other functions defined by series and integrals , 33C20 Generalized hypergeometric series, $_pF_q$

Language: ENG

Available: Pr-A-99-06.ps

Contact: Gorenflo, Rudolf; Freie Universität Berlin, Fachbereich Mathematik und Informatik, Arnimallee 2-6, D-14195 Berlin, Germany (gorenflo@math.fu-berlin.de)

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