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Sharp Estimates of Logarithmic Coefficients for a Certain Class of Starlike Functions

Complex Variables 2026-03-18 v1

Abstract

In this article, we investigate the extremal properties of logarithmic coefficients for the class Sch\mathcal{S}_{ch}^* of starlike functions associated with the hyperbolic cosine function. We establish the sharp upper bounds for the initial logarithmic coefficients γn\gamma_n for n=1,2,3n=1, 2, 3, and determine the precise bound for the second Hankel determinant H2,1(Ff/2)H_{2,1}(F_f/2) within this class. Furthermore, we extend our analysis to the inverse functions, deriving sharp estimates for the logarithmic inverse coefficients and the corresponding second Hankel determinant H2,1(Ff1/2)|H_{2,1}(F_{f^{-1}}/2)|. Additionally, we provide sharp bounds for the moduli differences of both logarithmic and inverse logarithmic coefficients. The sharpness of all obtained inequalities is verified through the construction of specific extremal functions.

Keywords

Cite

@article{arxiv.2603.15659,
  title  = {Sharp Estimates of Logarithmic Coefficients for a Certain Class of Starlike Functions},
  author = {Molla Basir Ahamed and Sanju Mandal},
  journal= {arXiv preprint arXiv:2603.15659},
  year   = {2026}
}

Comments

23 pages, 2 figures. arXiv admin note: substantial text overlap with arXiv:2502.02898