Lobachevskii Journal of Mathematics ( IF 0.8 ) Pub Date : 2020-12-30 , DOI: 10.1134/s1995080220110049 Seraj A. Alkhaleefah , Ilgiz R. Kayumov , Saminathan Ponnusamy
Abstract
In this paper we first consider another version of the Rogosinski inequality for analytic functions \(f(z)=\sum_{n=0}^{\infty}a_{n}z^{n}\) in the unit disk \(|z|<1\), in which we replace the coefficients \(a_{n}\) \((n=0,1,\ldots,N)\) of the power series by the derivatives \(f^{(n)}(z)/n!\) \((n=0,1,\ldots,N)\). Secondly, we obtain improved versions of the classical Bohr inequality and Bohr’s inequality for the harmonic mappings of the form \(f=h+\overline{g}\), where the analytic part \(h\) is bounded by \(1\) and that \(|g^{\prime}(z)|\leq k|h^{\prime}(z)|\) in \(|z|<1\) and for some \(k\in[0,1]\).
中文翻译:
有界解析函数的Bohr–Rogosinski不等式
摘要
在本文中,我们首先考虑Rogosinski不等式解析函数的另一个版本\(F(Z)= \ sum_ {N = 0} ^ {\ infty} A_ {N} Z 2 {N} \)在单位圆盘\ (| z | <1 \),其中我们将幂级数 的系数\(a_ {n} \)\((n = 0,1,\ ldots,N)\)替换为导数\(f ^ {(n)}(z)/ n!\) \((n = 0,1,\ ldots,N)\)。其次,对于形式为\(f = h + \ overline {g} \)的调和映射,我们获得了经典Bohr不等式和Bohr不等式的改进版本,其中分析部分\(h \)由\(1 \ )和\(| G ^ {\素}(Z)| \当量K | H ^ {\素}(Z)| \)在\(| Z | <1 \)和一些\(k \ in [0,1] \)。