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Zapiski Nauchnykh Seminarov LOMI, 1985, Volume 144, Pages 46–50
(Mi znsl5298)
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Ranges of values of some functionals on classes of regular functions
E. G. Goluzina
Abstract:
Let $P_{k, n}(\lambda,\beta)$ be the class of functions $g(z)=1+\sum^\infty_{\nu=n}c_\nu z^\nu$, regular in $B|z|<1$ and satisfying the condition
$$
\int^{2\pi}_0\left|\operatorname{Re}\left[e^{i\lambda}g(z)-\beta\cos\lambda\right]\Bigm/(1-\beta)\cos\lambda\right|d\theta\leq k\pi,\quad z=re^{i\theta},
$$
$0<r<1$ ($k\geq2$, $n\geq1$, $0\leq\beta<1$, $-\pi/2<\lambda<\pi/2$);
$M_{k,n}(\lambda,\beta,\alpha)$, $n\geq2$, is the class of functions $f(z)=z+\sum^{\infty}_{\nu=n}a_\nu z^\nu$, regular in $|z|<1$ and such that $F_\alpha(z)\in P_{k,n-1}(\alpha,\beta)$, where $F_\alpha(z)=(1-\alpha)\frac{zf^\prime(z)}{f(z)}+\alpha\Bigl(1+\frac{zf^{\prime\prime}(z)}{f^\prime(z)}\Bigr)$ ($0\leq\alpha\leq1$). Onr considers the problem regarding the range of the system $\{g^{(\nu-1)}(z_\ell)/(\nu-1)!\}$, $\ell=1,2,\dots,m$, $\nu=1,2,\dots,N_\ell$, on the class $P_{k,1}(\lambda,\beta)$. On the classes $P_{k,n}(\lambda,\beta)$, $M_{k,n}(\lambda,\beta,\alpha)$ one finds the ranges of $c_\nu$, $\nu\geq n$, $a_m$, $n\leq m\leq2n-2$, and $g(\zeta)$, $F_\alpha(\zeta)$, $0<|\zeta|<1$, $\zeta$ is fixed.
Citation:
E. G. Goluzina, “Ranges of values of some functionals on classes of regular functions”, Analytical theory of numbers and theory of functions. Part 6, Zap. Nauchn. Sem. LOMI, 144, "Nauka", Leningrad. Otdel., Leningrad, 1985, 46–50
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https://www.mathnet.ru/eng/znsl5298 https://www.mathnet.ru/eng/znsl/v144/p46
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