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JOURNALS // Zapiski Nauchnykh Seminarov POMI // Archive

Zap. Nauchn. Sem. POMI, 2012 Volume 405, Pages 59–66 (Mi znsl5278)

Estimating the second coefficient in the class of typically real functions with two function values prescribed

E. G. Goluzina

St. Petersburg Department of V. A. Steklov Institute of Mathematics, Russian Academy of Sciences, St. Petersburg, Russia

Abstract: Let $T_1$ be the class of functions $f(z)=z+c_2z^2+\cdots$ regular and typically real in the disk $|z|<1$ whose values $f(r_1)$ and $f(z_2)$ are fixed, $0<r_1<r_2<1$. Let $T_2$ be the class of functions $f(z)=z+c_2z^2+\cdots$ regular and typically real in the disk $|z|<1$ whose values $f(r_1)$ and $f(z_0)$ are fixed, $0<r_1<1$, $0<|z_0|<1$. Sharp estimates on the coefficient $c_2$ are obtained for the classes $T_1$ and $T_2$.

Key words and phrases: typical real function, the second coefficient.

UDC: 517.54

Received: 09.11.2012


 English version:
Journal of Mathematical Sciences (New York), 2013, 191:1, 31–35

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© Steklov Math. Inst. of RAS, 2024