Starlikeness associated with parabolic regions

A parabolic starlike function f of order ρ in the unit disk is characterized by the fact that the quantity zf′(z)/f(z) lies in a given parabolic region in the right half-plane. Denote the class of such functions by PS∗(ρ). This class is contained in the larger class of starlike functions of order ρ....

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Main Author: Rosihan M. Ali
Format: Article
Language:English
Published: Wiley 2005-01-01
Series:International Journal of Mathematics and Mathematical Sciences
Online Access:http://dx.doi.org/10.1155/IJMMS.2005.561
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author Rosihan M. Ali
author_facet Rosihan M. Ali
author_sort Rosihan M. Ali
collection DOAJ
description A parabolic starlike function f of order ρ in the unit disk is characterized by the fact that the quantity zf′(z)/f(z) lies in a given parabolic region in the right half-plane. Denote the class of such functions by PS∗(ρ). This class is contained in the larger class of starlike functions of order ρ. Subordination results for PS∗(ρ) are established, which yield sharp growth, covering, and distortion theorems. Sharp bounds for the first four coefficients are also obtained. There exist different extremal functions for these coefficient problems. Additionally, we obtain a sharp estimate for the Fekete-Szegö coefficient functional and investigate convolution properties for PS∗(ρ).
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institution Kabale University
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1687-0425
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publishDate 2005-01-01
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series International Journal of Mathematics and Mathematical Sciences
spelling doaj-art-27f2064da0cd45e4a844c809432da1602025-02-03T05:51:33ZengWileyInternational Journal of Mathematics and Mathematical Sciences0161-17121687-04252005-01-012005456157010.1155/IJMMS.2005.561Starlikeness associated with parabolic regionsRosihan M. Ali0School of Mathematical Sciences, Universiti Sains Malaysia, Penang 11800, MalaysiaA parabolic starlike function f of order ρ in the unit disk is characterized by the fact that the quantity zf′(z)/f(z) lies in a given parabolic region in the right half-plane. Denote the class of such functions by PS∗(ρ). This class is contained in the larger class of starlike functions of order ρ. Subordination results for PS∗(ρ) are established, which yield sharp growth, covering, and distortion theorems. Sharp bounds for the first four coefficients are also obtained. There exist different extremal functions for these coefficient problems. Additionally, we obtain a sharp estimate for the Fekete-Szegö coefficient functional and investigate convolution properties for PS∗(ρ).http://dx.doi.org/10.1155/IJMMS.2005.561
spellingShingle Rosihan M. Ali
Starlikeness associated with parabolic regions
International Journal of Mathematics and Mathematical Sciences
title Starlikeness associated with parabolic regions
title_full Starlikeness associated with parabolic regions
title_fullStr Starlikeness associated with parabolic regions
title_full_unstemmed Starlikeness associated with parabolic regions
title_short Starlikeness associated with parabolic regions
title_sort starlikeness associated with parabolic regions
url http://dx.doi.org/10.1155/IJMMS.2005.561
work_keys_str_mv AT rosihanmali starlikenessassociatedwithparabolicregions