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Some estimates in the class of analytic functions of bounded type
V. P. Vazhdaev, S. A. Gel'fer
Abstract:
We consider the class $A_M$ of functions regular in the disk $|\zeta|<1$ which for any $r$, $0\leqslant r<1$, satisfy the condition
$$
\int_0^{2\pi}\ln^+|f(re^{i\theta})|\,d\theta\leqslant2\pi M,
$$
where $M$ does not depend on the function. Using a parametric representation of this class, the authors find exact estimates of the mean arithmetic value and the mean geometric value of the modulus of the function at equally spaced points of the circumference, estimates of the moduli and arguments of the function, the moduli of the derivatives and other values for the class $A_M$ and certain of its subclasses.
The solution of these problems is based on variation formulas introduced earlier by one of the authors (RZhMat., 1967, 11B99).
Bibliography: 14 titles.
Received: 23.02.1970
Citation:
V. P. Vazhdaev, S. A. Gel'fer, “Some estimates in the class of analytic functions of bounded type”, Math. USSR-Sb., 13:2 (1971), 267–284
Linking options:
https://www.mathnet.ru/eng/sm3070https://doi.org/10.1070/SM1971v013n02ABEH001037 https://www.mathnet.ru/eng/sm/v126/i2/p273
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