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JOURNALS // Matematicheskii Sbornik // Archive

Mat. Sb., 1991 Volume 182, Number 11, Pages 1523–1541 (Mi sm1386)

This article is cited in 16 papers

Numerical results on best uniform rational approximation of $|x|$ on $[-1,1]$

R. S. Vargaa, A. Ruttana, A. J. Carpenterb

a Kent State University
b Butler University

Abstract: With $E_{n,n}(|x|;[-1,1])$ denoting the error of best uniform rational approximation from $\pi_{n,n}$ to $|x|$ on $[-1,1]$, we determine the numbers $\{E_{2n,2n}(|x|;[-1,1])\}_{n=1}^{40}$, where each of these numbers was calculated with a precision of at least 200 significant digits. With these numbers, the Richardson extrapolation method was applied to the products $\{e^{\pi\sqrt{2n}}E_{2n,2n}(|x|;[-1,1])\}_{n=1}^{40}$, and it appears, to at least 10 significant digits, that
$$ 8\stackrel{?}{=}\lim_{n\to\infty}e^{\pi\sqrt{2n}}E_{2n,2n}(|x|;[-1,1]), $$
which gives rise to an interesting new conjecture in the theory of rational approximation.

UDC: 517.53

MSC: 41A20, 41A50, 65D10

Received: 12.10.1990


 English version:
Mathematics of the USSR-Sbornik, 1993, 74:2, 271–290

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