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Fundamentalnaya i Prikladnaya Matematika, 1995, Volume 1, Issue 3, Pages 581–612
(Mi fpm88)
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This article is cited in 1 scientific paper (total in 1 paper)
New examples of nonnegative trigonometric polynomials with integer coefficients
A. S. Belov Ivanovo State University
Abstract:
In the paper it is proved that for any positive integer $n$ and any number $\lambda\geq1$ the following estimate holds:
$$
2\lambda n^{\alpha}+\sum_{k=1}^{s}\Bigl[\lambda\left(\frac{n}{k}\right)^{\alpha}-1\Bigr]\cos(kx)>0
$$
for all $x$ and $s=0,\ldots,n$. Here the braces mean the integer part of a number, and $\alpha\in(0,1)$ is the unique root of the equation $\int_{0}^{3\pi/2}t^{-\alpha}\cos t\,dt=0$. It is proved also that for any positive integer $n$ and any numbers $q\geq2$ and $\lambda \geq sq^q$ the following estimate is true:
$$
4\lambda n^{1/q}+\sum_{k=1}^{n}\Bigl[\lambda\Bigl(\left(
\frac{n}{k}\right)^{1/q}-1\Bigr)+1\Bigl]\cos(kx)>0
$$
for all $x$. From these two main results and similar ones new estimates in some extremal problems connected with nonnegative trigonometric polynomials with integer coefficients are deduced.
Received: 01.04.1995
Citation:
A. S. Belov, “New examples of nonnegative trigonometric polynomials with integer coefficients”, Fundam. Prikl. Mat., 1:3 (1995), 581–612
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https://www.mathnet.ru/eng/fpm88 https://www.mathnet.ru/eng/fpm/v1/i3/p581
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Abstract page: | 482 | Full-text PDF : | 165 | References: | 80 | First page: | 2 |
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