• Title/Summary/Keyword: Zalcman inequality

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COEFFICIENT INEQUALITIES FOR A UNIFIED CLASS OF BOUNDED TURNING FUNCTIONS ASSOCIATED WITH COSINE HYPERBOLIC FUNCTION

  • Gagandeep Singh;Gurcharanjit Singh;Navyodh Singh;Navjeet singh
    • The Pure and Applied Mathematics
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    • v.31 no.2
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    • pp.201-216
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    • 2024
  • The aim of this paper is to study a new and unified class 𝓡αCosh of analytic functions associated with cosine hyperbolic function in the open unit disc E = {z ∈ ℂ : |z| < 1}. Some interesting properties of this class such as initial coefficient bounds, Fekete-Szegö inequality, second Hankel determinant, Zalcman inequality and third Hankel determinant have been established. Furthermore, these results have also been studied for two-fold and three-fold symmetric functions.

Some Coefficient Inequalities Related to the Hankel Determinant for a Certain Class of Close-to-convex Functions

  • Sun, Yong;Wang, Zhi-Gang
    • Kyungpook Mathematical Journal
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    • v.59 no.3
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    • pp.481-491
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    • 2019
  • In the present paper, we investigate the upper bounds on third order Hankel determinants for certain class of close-to-convex functions in the unit disk. Furthermore, we obtain estimates of the Zalcman coefficient functional for this class.

HANKEL DETERMINANT PROBLEMS FOR CERTAIN SUBCLASSES OF SAKAGUCHI TYPE FUNCTIONS DEFINED WITH SUBORDINATION

  • Singh, Gagandeep;Singh, Gurcharanjit
    • Korean Journal of Mathematics
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    • v.30 no.1
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    • pp.81-90
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    • 2022
  • The present investigation is concerned with the estimation of initial coefficients, Fekete-Szegö inequality, second Hankel determinants, Zalcman functionals and third Hankel determinants for certain subclasses of Sakaguchi type functions defined with subordination in the open unit disc E = {z ∈ ℂ : |z| < 1}. The results derived in this paper will pave the way for the further study in this direction.