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Quantitative Voronovskaya-Type Theorems for Fejér-Korovkin Operators

Year 2020, Volume: 3 Issue: 4, 150 - 164, 01.12.2020
https://doi.org/10.33205/cma.818715

Abstract

In recent times quantitative Voronovskaya type theorems have been presented in
spaces of non-periodic continuous functions. In this work we proved similar results
but for Fejér-Korovkin trigonometric operators. That is we measure the rate of convergence
in the associated Voronovskaya type theotem. Recall that these operators provide the optimal rate in approximation
by positive linear operators. For the proofs we present new
inequalities related with trigonometric polynomials as well as with the convergence factor
of the Fej\'er-Korovkin operators. Our approach includes spaces of
Lebesgue integrable functions.

Supporting Institution

I have not received support.

References

  • J. Bustamante, L. Flores-de-Jesús: Strong converse inequalities and quantitative Voronovskaya-type theorems for trigonometric Fejér sums. Constr. Math. Anal. 3 (2) (2020), 53-63.
  • P. L. Butzer, E. Gorlich: Saturationsklassen und asymptotische Eigenschaften trigonometrischer singulärer Integrale. (German), 1966 Festschr. Gedächtnisfeier K.Weierstrass, Westdeutscher Verlag, Cologne, 339–392.
  • P. L. Butzer, R. J. Nessel: Fourier Analysis and Approximation. New York-Base1 (1971).
  • P. L. Butzer, E. L. Stark: On a trigonometric convolution operator with kernels having two zeros of simple multiplicity. Acta Math. Acad. Sci. Hung. 20 (1969), 451-461.
  • S. Foucart, Y. Kryakin and A. Shadrin: On the exact constant in the Jackson-Stechkin inequality for the uniform metric. Constr. Approx. 29 (2009), 157-179.
  • P. P. Korovkin: An asymptotic property of positive methods of summation of Fourier series and best approximation of functions of class Z2 by linear positive polynomial operators. (in Russian), Uspehi Mat. Nauk 6 (84) (1958), 99-103.
  • I. M. Petrov: Order of approximation of functions of the class Z for some polynomial operators. (in Russian), Uspehi Mat. Nauk 13 (84) (1958), 127-131.
  • E. L. Stark: The kernel of Fejér-Korovkin: a basic tool in the constructive theory of functions. Functions, series, operators, Vol. I, II (Budapest, 1980), Colloq. Math. Soc. János Bolyai, 35, North-Holland, Amsterdam, 1983, 1095-1123.
  • A. F. Timan: Theory of Approximation of Functions of Real Variable. Pergamon Press, 1963.
  • A. Zygmund: Trigonometric series. Third Edition, Vol I and II combined, Cambridge Mathematical Library, 2002.
Year 2020, Volume: 3 Issue: 4, 150 - 164, 01.12.2020
https://doi.org/10.33205/cma.818715

Abstract

References

  • J. Bustamante, L. Flores-de-Jesús: Strong converse inequalities and quantitative Voronovskaya-type theorems for trigonometric Fejér sums. Constr. Math. Anal. 3 (2) (2020), 53-63.
  • P. L. Butzer, E. Gorlich: Saturationsklassen und asymptotische Eigenschaften trigonometrischer singulärer Integrale. (German), 1966 Festschr. Gedächtnisfeier K.Weierstrass, Westdeutscher Verlag, Cologne, 339–392.
  • P. L. Butzer, R. J. Nessel: Fourier Analysis and Approximation. New York-Base1 (1971).
  • P. L. Butzer, E. L. Stark: On a trigonometric convolution operator with kernels having two zeros of simple multiplicity. Acta Math. Acad. Sci. Hung. 20 (1969), 451-461.
  • S. Foucart, Y. Kryakin and A. Shadrin: On the exact constant in the Jackson-Stechkin inequality for the uniform metric. Constr. Approx. 29 (2009), 157-179.
  • P. P. Korovkin: An asymptotic property of positive methods of summation of Fourier series and best approximation of functions of class Z2 by linear positive polynomial operators. (in Russian), Uspehi Mat. Nauk 6 (84) (1958), 99-103.
  • I. M. Petrov: Order of approximation of functions of the class Z for some polynomial operators. (in Russian), Uspehi Mat. Nauk 13 (84) (1958), 127-131.
  • E. L. Stark: The kernel of Fejér-Korovkin: a basic tool in the constructive theory of functions. Functions, series, operators, Vol. I, II (Budapest, 1980), Colloq. Math. Soc. János Bolyai, 35, North-Holland, Amsterdam, 1983, 1095-1123.
  • A. F. Timan: Theory of Approximation of Functions of Real Variable. Pergamon Press, 1963.
  • A. Zygmund: Trigonometric series. Third Edition, Vol I and II combined, Cambridge Mathematical Library, 2002.
There are 10 citations in total.

Details

Primary Language English
Subjects Mathematical Sciences
Journal Section Articles
Authors

Jorge Bustamante 0000-0003-2856-6738

Lázaro Flores De Jesús 0000-0002-3431-5903

Publication Date December 1, 2020
Published in Issue Year 2020 Volume: 3 Issue: 4

Cite

APA Bustamante, J., & Flores De Jesús, L. (2020). Quantitative Voronovskaya-Type Theorems for Fejér-Korovkin Operators. Constructive Mathematical Analysis, 3(4), 150-164. https://doi.org/10.33205/cma.818715
AMA Bustamante J, Flores De Jesús L. Quantitative Voronovskaya-Type Theorems for Fejér-Korovkin Operators. CMA. December 2020;3(4):150-164. doi:10.33205/cma.818715
Chicago Bustamante, Jorge, and Lázaro Flores De Jesús. “Quantitative Voronovskaya-Type Theorems for Fejér-Korovkin Operators”. Constructive Mathematical Analysis 3, no. 4 (December 2020): 150-64. https://doi.org/10.33205/cma.818715.
EndNote Bustamante J, Flores De Jesús L (December 1, 2020) Quantitative Voronovskaya-Type Theorems for Fejér-Korovkin Operators. Constructive Mathematical Analysis 3 4 150–164.
IEEE J. Bustamante and L. Flores De Jesús, “Quantitative Voronovskaya-Type Theorems for Fejér-Korovkin Operators”, CMA, vol. 3, no. 4, pp. 150–164, 2020, doi: 10.33205/cma.818715.
ISNAD Bustamante, Jorge - Flores De Jesús, Lázaro. “Quantitative Voronovskaya-Type Theorems for Fejér-Korovkin Operators”. Constructive Mathematical Analysis 3/4 (December 2020), 150-164. https://doi.org/10.33205/cma.818715.
JAMA Bustamante J, Flores De Jesús L. Quantitative Voronovskaya-Type Theorems for Fejér-Korovkin Operators. CMA. 2020;3:150–164.
MLA Bustamante, Jorge and Lázaro Flores De Jesús. “Quantitative Voronovskaya-Type Theorems for Fejér-Korovkin Operators”. Constructive Mathematical Analysis, vol. 3, no. 4, 2020, pp. 150-64, doi:10.33205/cma.818715.
Vancouver Bustamante J, Flores De Jesús L. Quantitative Voronovskaya-Type Theorems for Fejér-Korovkin Operators. CMA. 2020;3(4):150-64.