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On the constancy of signs and order of magnitude of Fourier–Haar coefficients

  • Larry Gogoladze and Vakhtang Tsagareishvili EMAIL logo
Published/Copyright: June 16, 2018
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Abstract

In the paper, we investigate the relation between the properties of functions and their Fourier–Haar coefficients. We show that for some classes of functions Fourier–Haar coefficients have constant signs and order of magnitude. In 1964, Golubov proved in [B. I. Golubov, On Fourier series of continuous functions with respect to a Haar system (in Russian), Izv. Akad. Nauk SSSR Ser. Mat. 28 1964, 1271–1296] that if f(x)C(0,1), then its Fourier–Haar coefficients have constant signs when f(x) is a nonincreasing function on [0,1], and in some cases those coefficients have a certain order of magnitude. In the present paper, we continue to investigate the properties of functions which follow from the behavior of their Fourier–Haar coefficients.

MSC 2010: 42C10

Award Identifier / Grant number: FR/102/5-100/14

Funding statement: The work was supported by the Shota Rustaveli National Science Foundation grant number FR/102/5-100/14.

References

[1] G. Alexits, Convergence Problems of Orthogonal Series, Internat. Ser. Monogr. Pure Appl. Math. 20, Pergamon Press, New York, 1961. 10.1016/B978-1-4831-9774-6.50009-5Search in Google Scholar

[2] B. I. Golubov, On Fourier series of continuous functions with respect to a Haar system (in Russian), Izv. Akad. Nauk SSSR Ser. Mat. 28 (1964), 1271–1296. Search in Google Scholar

[3] V. Tsagareishvili, On the order of magnitude of Haar–Fourier coefficients, Anal. Math. 35 (2009), 301–316. 10.1007/s10476-009-0405-9Search in Google Scholar

[4] P. L. Ul’janov, On Haar series (in Russian), Mat. Sb. (N.S.) 63(105) (1964), 356–391. Search in Google Scholar

Received: 2016-03-07
Revised: 2016-05-27
Accepted: 2016-06-17
Published Online: 2018-06-16
Published in Print: 2018-09-01

© 2018 Walter de Gruyter GmbH, Berlin/Boston

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