On Sharp Coefficients and Hankel Determinants for a Novel Class of Analytic Functions

In this article, a new subclass of starlike functions is defined by using the technique of subordination and introducing a novel generalized domain. This domain is obtained by taking the composition of trigonometric <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML"...

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Bibliographic Details
Main Authors: Dong Liu, Adeel Ahmad, Huma Ikhlas, Saqib Hussain, Saima Noor, Huo Tang
Format: Article
Language:English
Published: MDPI AG 2025-03-01
Series:Axioms
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Online Access:https://www.mdpi.com/2075-1680/14/3/191
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Summary:In this article, a new subclass of starlike functions is defined by using the technique of subordination and introducing a novel generalized domain. This domain is obtained by taking the composition of trigonometric <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>sin</mi><mi>e</mi></mrow></semantics></math></inline-formula> function and the well known curve called lemniscate of Bernoulli which is the image of open unit disc under a function <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>g</mi><mfenced open="(" close=")"><mi>ξ</mi></mfenced><mo>=</mo><msqrt><mrow><mn>1</mn><mo>+</mo><mi>ξ</mi></mrow></msqrt></mrow></semantics></math></inline-formula>. This domain is characterized by its pleasing geometry which exhibits symmetric about the real axis. For this newly defined subclass, we investigate the sharp upper bounds for its first four coefficients, as well as the second and third order Hankel determinants.
ISSN:2075-1680