Exact order of approximation of periodic functions by one nonclassical method of summation of Fourier series
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- Kotova, O.V. & Trigub, R.M. Ukr Math J (2012) 64: 1090. doi:10.1007/s11253-012-0701-6
By using an exact estimate for approximation by known trigonometric polynomials, we strengthen a Jackson-type theorem. Moreover, we determine the exact order of approximation of some periodic functions by these polynomials. For this purpose, we introduce a special modulus of smoothness.