Criteria for strongly starlike functions
作者:
S. Ponnusamy,
Vikramaditya Singh,
期刊:
Complex Variables, Theory and Application: An International Journal
(Taylor Available online 1997)
卷期:
Volume 34,
issue 3
页码: 267-291
ISSN:0278-1077
年代: 1997
DOI:10.1080/17476939708815053
出版商: Gordon and Breach Science Publishers
关键词: Univalent;starlike;strongly starlike and subordination;30C45;30C80
数据来源: Taylor
摘要:
LetAnbe the family of normalized regular functions f, where f(z)=z+an+1zn+1+…, in the unit disc Δ and letS(α) andTλbe the families of functionsfsuch thatrespectively.S(α) is the class of strongly starlike functions. Further, letS*(α) denote the well-known family of starlike functions of order α. The purpose of this paper is to find conditions so that 1.satisfyingsatisfying. 2.satisfyingis inS(α) or in3.satisfyingis inS(α) or inS*(α); 4.satisfying Re f′(z)≥1−λ1,|g′(z)−1|≤λ2, implyz(f*g)′ is inS(α). The results of this paper extend the previously known results and improve some criteria for starlike functions. These are then used to obtain new information for uniformly convex functions and Bemardi integral transform.
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