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JOURNALS // Vestnik Tomskogo Gosudarstvennogo Universiteta. Matematika i Mekhanika // Archive

Vestn. Tomsk. Gos. Univ. Mat. Mekh., 2023 Number 85, Pages 5–21 (Mi vtgu1025)

MATHEMATICS

On the generalization of some classes of close-to-convex and typically real functions

F. F. Maiyer, M. G. Tastanov, A. A. Utemissova, A. T. Baimankulov

Kostanay Regional University named after A. Baitursynov, Kostanay, Kazakhstan

Abstract: he paper introduces the class $C(\lambda,\alpha,\gamma)=\left\{f(z) :\left| (1-\lambda z^2)f'(z)^{1/\gamma}-a\right|\leqslant a\right\}$, $0\leqslant\lambda\leqslant 1$, $0\leqslant\gamma\leqslant 1$, $a>1/2$, almost convex order for functions, generalizing classes of functions with limited rotation $(a\to+\infty, \lambda=0)$ and functions convex of order $\gamma$ in the direction of the imaginary axis $(a\to+\infty, \lambda=1)$.
For the class $C(\lambda, a, \gamma)$ and its subclasses, unimprovable distortion theorems and exact convexity radii are found, and similar results are obtained in a class generalizing the class of typically real functions.

Keywords: geometric theory of functions, single-leaf functions, estimates of analytic functions, typically real functions, radii of convexity.

UDC: 517.54

MSC: 30C45

Received: 27.02.2023
Accepted: October 10, 2023

DOI: 10.17223/19988621/85/1



© Steklov Math. Inst. of RAS, 2024