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JOURNALS // Problemy Fiziki, Matematiki i Tekhniki (Problems of Physics, Mathematics and Technics) // Archive

PFMT, 2021 Issue 2(47), Pages 81–83 (Mi pfmt784)

MATHEMATICS

Trigonometric Padé approximants of special functions

N. V. Ryabchenko

Francisk Skorina Gomel State University

Abstract: For the functions $H_\gamma=\sum_{k=1}^\infty\sin kx/(\gamma)_k$, where $(\gamma)_k=\gamma(\gamma+1)\cdots(\gamma+k-1)$ and their trigonometric Padé approximations $\pi^t_{n,m}(x;H_\gamma)$ the asymptotics of decreasing difference $H_\gamma(x)-\pi^t_{n,m}(x;H_\gamma)$ in the case is found, where $0\leqslant m\leqslant m(n)$, $m(n)=o(n)$, as $n\to\infty$. Particulary, we determine that, under the same assumption, the trigonometric Padé approximations $\pi^t_{n,m}(x;H_\gamma)$ converge to $H_\gamma$ uniformly on the $\mathbb{R}$ with the asymptotically best rate.

Keywords: Padé approximations, asymptotic equality, best uniform approximation, trigonometric Padé approximations, rational approximations.

UDC: 517.538.52+517.538.53

Received: 05.03.2021



© Steklov Math. Inst. of RAS, 2024