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JOURNALS // Vestnik Moskovskogo Universiteta. Seriya 1. Matematika. Mekhanika // Archive

Vestnik Moskov. Univ. Ser. 1. Mat. Mekh., 2009 Number 4, Pages 35–41 (Mi vmumm887)

This article is cited in 1 paper

Mathematics

Localization of small zeros of sine and cosine Fourier transforms of a finite positive nondecreasing function

A. M. Sedletskii

Lomonosov Moscow State University, Faculty of Mechanics and Mathematics

Abstract: Let a function $f$ be integrable, positive, and nondecreasing in the interval $(0,1)$. Then by Polya's theorem all zeros of the corresponding cosine- and sine-Fourier transforms are real and simple; in this case positive zeros lie in the intervals $(\pi(n-1/2),\pi(n+1/2)),\;(\pi n,\pi(n+1)),\;n\in\mathbb{N},$ respectively. In the case of the sine-transforms it is required that $f$ cannot be a stepped function with retional discontinuity points. In this paper, zeros of the function with small numbers are included into intervals being proper subsets of the corresponding Polya intervals. A localization of small zeros of the Mittag-Leffler function $E_{1/2}(-z^2;\mu),\,\mu\in(1,2)\cup(2,3)$ is obtained as a corollary.

Key words: sine- and cosine-Fourier transform, zeros of entire function, Mittag-Leffler's function.

UDC: 517.547.28



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