Univalence and starlikeness of certain transforms defined by convolution of analytic functions

被引:40
|
作者
Obradovic, M.
Ponnusamy, S.
机构
[1] Fac Civil Engn, Dept Math, Belgrade 11000, Serbia
[2] Indian Inst Technol, Dept Math, Madras 600036, Tamil Nadu, India
关键词
univalent; starlike and convex functions;
D O I
10.1016/j.jmaa.2007.03.020
中图分类号
O29 [应用数学];
学科分类号
070104 ;
摘要
Let U(lambda) denote the class of all analytic functions f in the unit disk Delta of the form f (z) = z + a(2)z(2) + ... satisfying the condition f(z)(z/f(z))(2) -1 vertical bar <= lambda, z is an element of Delta. In this paper we find conditions on lambda and on c is an element of C with Rec >= 0 not equal c such that for each f is an element of u(lambda) satisfying (z/f (z))*F(1, c; c + 1; z) not equal 0 for all z is an element of Delta the transform G(z) = G(f)(c) (z) = z/(z/f(z))*F(1, c; c + 1; z), z is an element of Delta, is univalent or starlike. Here F(a, b; c; z) denotes the Gauss hypergeometric function and * denotes the convolution (or Hadamard product) of analytic functions on Delta. (c) 2007 Elsevier Inc. All rights reserved.
引用
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页码:758 / 767
页数:10
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