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This article is cited in 9 scientific papers (total in 9 papers)
On a conjecture of S. Bernstein in approximation theory
R. S. Varga, A. J. Carpenter
Abstract:
With $E_{2n}(|x|)$ denoting the error of best uniform approximation to $|x|$ by polynomials of degree at most $2n$ on the interval $[-1,1]$, the famous Russian mathematician S. Bernstein in 1914 established the existence of a positive constant $\beta$ for which
$$
\lim_{n\to\infty}(2nE_{2n}(|x|))=:\beta.
$$
Moreover, by means of numerical calculations, Bernstein determined, in the same paper, the following upper and lower bounds for $\beta$: $0,278<\beta<0,286$ Now, the average of these bounds is 0.282, which, as Bernstein noted as a “curious coincidence”, is very close to $\frac1{2\sqrt\pi}=0,2820947917\dots$. This observation has over the years become known as
The Bernstein Conjecture. {\it Is $\beta=\frac1{2\sqrt\pi}?$}
We show here that the Bernstein conjecture is false. In addition, we determine rigorous upper and lower bounds for $\beta$, and by means of the Richardson extrapolation procedure, estimate $\beta$ to approximately 50 decimal places.
Tables: 4.
Bibliography: 12 titles.
Received: 27.03.1985
Citation:
R. S. Varga, A. J. Carpenter, “On a conjecture of S. Bernstein in approximation theory”, Math. USSR-Sb., 57:2 (1987), 547–560
Linking options:
https://www.mathnet.ru/eng/sm1844https://doi.org/10.1070/SM1987v057n02ABEH003086 https://www.mathnet.ru/eng/sm/v171/i4/p535
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