FOURTH HANKEL DETERMINANT FOR A NEW SUBCLASS OF BOUNDED TURNING FUNCTIONS 

By

Gaganpreet Kaur1 and Gurmeet Singh2

1Department of Mathematics, Punjabi university Patiala-147002, Punjab, India 

2Department of Mathematics, GSSDGS Khalsa College Patiala-147001, Punjab, India 

Email:gaganpreet_rs18@pbi.ac.in,meetgur111@gmail.com 

(Received: March 03, 2021; Revised: March 23, 2021; Accepted : May 30, 2022) 

  DOI: https://doi.org/10.58250/Jnanabha.2022.52129

Abstract

In this paper, we consider a new subfamily of holomorphic (analytic) functions with bounded turning in the open unit disk U = {z; |z| < 1}. Here, in this paper, we focus the coefficient estimates and upper bounds of fourth Hankel determinant for this family. Moreover, the same bounds have been investigated for two-fold and three-fold symmetric functions. 

2020 Mathematical Sciences Classification: 30C45, 30C50. 

Keywords and Phrases: Analytic function, Bounded turning functions, Hankel determinant, m-fold symmetric function