Abstract
In this paper we study the exponential uniform strong approximation of Marcinkiewicz type of two-dimensional Walsh–Kaczmarz–Fourier series. In particular, it is proved that the Marcinkiewicz type of two-dimensional Walsh–Kaczmarz–Fourier series of every continuous function f is uniformly strong summable to the function f exponentially in the power 1/2. Moreover, it is proved that this result is the best possible.
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A. Alexits and D. Králik, Über den Annäherungagred der Approximation im starken Sinne von stetigen Funktionen, Magyar Tud. Akad. Mat. Kut. Int. Közl., 8 (1963), 317–327.
L. Fejér, Untersuchungen Über Fouriersche Reihen, Math. Ann., 58 (1904), 501–569.
S. Fridli, On integrability and strong summability of Walsh–Kaczmarz series, Anal. Math., 40 (2014), 197–214.
S. Fridli and F. Schipp, Strong summability and Sidon type inequality, Acta Sci. Math. (Szeged), 60 (1985), 277–289.
S. Fridli and F. Schipp, Strong approximation via Sidon type inequalities, J. Approx. Theory, 94 (1998), 263–284.
G. Gát, U. Goginava and G. Karagulyan, Almost everywhere strong summability of Marcinkiewicz means of double Walsh–Fourier series, Anal. Math., 40 (2014), 243–266.
G. Gát, U. Goginava and G. Karagulyan, On everywhere divergence of the strong F-means of Walsh–Fourier series, J. Math. Anal. Appl., 421 (2015), 206–214.
G. Gát and K. Nagy, On the (C, a)-means of quadratical partial sums of double Walsh–Kaczmarz–Fourier series, Georgian Math. J., 16 (2009) 489–506.
V. A. Glukhov, Summation of multiple Fourier series in multiplicative systems, Mat. Zametki, 39(5) (1986), 665–673 (in Russian).
L. Gogoladze, On the exponential uniform strong summability of multiple trigonometric Fourier series, Georgian Math. J., 16 (2009), 517–532.
U. Goginava, Convergence in measure of partial sums of double Vilenkin–Fourier series, Georgian Math. J., 16 (2009), 507–516.
U. Goginava and L. Gogoladze, Strong approximation by Marcinkiewicz means of twodimensional Walsh–Fourier series, Constr. Approx., 35 (2012), 1–19.
U. Goginava, L. Gogoladze, Strong approximation of two-dimensional Walsh–Fourier series, Studia Sci. Math. Hungar., 49 (2012), 170–188.
U. Goginava, L. Gogoladze and G. Karagulyan, BMO-estimation and almost everywhere exponential summability of quadratic partial sums of double Fourier series, Constr. Approx., 40 (2014), 105–120.
U. Goginava, Almost everywhere convergence of (C,a)-means of cubical partial sums of d-dimensional Walsh–Fourier series, J. Approx. Theory, 141 (2006), 8–28.
U. Goginava, The weak type inequality for the Walsh system, Studia Math., 185 (2008), 35–48.
G. H. Hardy and J. E. Littlewood, Sur la serie de Fourier d’une fonction à carré sommable, C. R. Acad. Sci. Paris, 156 (1913), 1307–1309.
K. Nagy, On the two-dimensional Marcinkiewicz means with respect to Walsh–Kaczmarz system, J. Approx. Theory, 142 (2006) 138–165.
L. Leindler, Über die Approximation im starken Sinne, Acta Math. Acad. Sci. Hungar., 16 (1965), 255–262.
L. Leindler, On the strong approximation of Fourier series, Acta Sci. Math. (Szeged), 38 (1976), 317–324.
L. Leindler, Strong approximation and classes of functions, Mitt. Math. Sem. Giessen, 132 (1978), 29–38.
L. Leindler, Strong Approximation by Fourier Series, Akadémiai Kiadó Budapest, 1985).
V. A. Rodin, BMO-strong means of Fourier series, Funct. Anal. Appl., 23 (1989), 73–74 (in Russian).
F. Schipp, Über die starke Summation von Walsh–Fourier Reihen, Acta Sci. Math. (Szeged), 30 (1969), 77–87.
F. Schipp, On strong approximation of Walsh–Fourier series, MTA III. Oszt. Közl., 19 (1969), 101–111 (in Hungarian).
F. Schipp and N. X. Ky, On strong summability of polynomial expansions, Anal. Math., 12 (1986), 115–128.
F. Schipp, W. R. Wade, P. Simon and J. Pál, Walsh Series. An Introduction to Dyadic Harmonic Analysis, Adam Hilger Bristol, New York, 1990).
V. A. Skvortsov, On Fourier series with respect to the Walsh–Kaczmarz system, Anal. Math., 7 (1981), 141–150.
V. Totik, On the strong approximation of Fourier series, Acta Math. Sci. Hungar., 35 (1980), 151–172.
V. Totik, On the generalization of Fejér’s summation theorem, Functions, Series, Operators; Coll. Math. Soc. J. Bolyai (Budapest) Hungary, 35, North Holland (Amsterdam, Oxford, New-York, 1980), pp. 1195–1199.
V. Totik, Notes on Fourier series: Strong approximation, J. Approx. Theory, 43 (1985), 105–111.
F. Weisz, Strong summability of Ciesielski–Fourier series, Studia Math., 161 (2004), 269–302.
F. Weisz, Strong summability of more-dimensional Ciesielski–Fourier series, East J. Approx., 10 (2004), 333–354.
F. Weisz, Summability of Multi-dimensional Fourier Series and Hardy Space, Kluwer Academic Publisher Dordrecht, 2002).
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The research of first author was supported by Shota Rustaveli National Science Foundation grant no. DI/9/5-100/13 (Function spaces, weighted inequalities for integral operators and problems of summability of Fourier series).
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Goginava, U., Nagy, K. Strong approximation by Marcinkiewicz means of two-dimensional Walsh–Kaczmarz–Fourier series. Anal Math 42, 143–157 (2016). https://doi.org/10.1007/s10476-016-0203-0
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DOI: https://doi.org/10.1007/s10476-016-0203-0