On a coefficient body for concave functions
On a coefficient body for concave functions
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关于凹函数的系数体
DOI:
10.1007/s40315-013-0018-y
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发表时间:
2013
影响因子:
2.1
通讯作者:
Rintaro Ohno and Hiroshi Yanagihara
中科院分区:
文献类型:
--
作者:
K.Mitani;K.-S.Saito;Y.Takahashi;Rintaro Ohno and Hiroshi Yanagihara
Forletbe the class of meromorphic and univalent functionsin the unit diskwith a simple pole atsuch thatis convex. These so-called concave functions can be expanded as $$\begin{aligned} f(z)= \sum _{n=0}^{\infty } a_n(f)z^n, \quad |z|<p \end{aligned}$$or $$\begin{aligned} f(z)= \sum _{n=-1}^{\infty } c_n(f) (z-p)^n, \quad |z-p|<1-p. \end{aligned}$$The present article shows a representation formula for functions of class, using functions of positive real part, and gives an explicit description of the coefficient body $$\begin{aligned} \left\{ a_1(f), c_{-1}(f), c_1(f) \right\} . \end{aligned}$$