English

Sharp Bounds of Fifth Coefficient and Hermitian-Toeplitz determinants for Sakaguchi Classes

Complex Variables 2022-10-25 v1

Abstract

For the classes of analytic functions ff defined on the unit disk satisfying zf(z)f(z)f(z)φ(z)and(2zf(z))(f(z)f(z))φ(z),\frac{z {f}'(z)}{f(z) - f(-z)} \prec \varphi(z) \quad \text{and} \quad \frac{(2 z {f}'(z))'}{(f(z) - f(-z))'} \prec \varphi(z), denoted by Ss(φ)\mathcal{S}^*_s(\varphi) and Cs(φ)\mathcal{C}_s(\varphi) respectively, the sharp bound of the nthn^{th} Taylor coefficients are known for n=2,n=2, 33 and 44. In this paper, we obtain the sharp bound of the fifth coefficient. Additionally, the sharp lower and upper estimates of the third order Hermitian Toeplitz determinant for the functions belonging to these classes are determined. The applications of our results lead to the establishment of certain new and previously known results.

Keywords

Cite

@article{arxiv.2210.13170,
  title  = {Sharp Bounds of Fifth Coefficient and Hermitian-Toeplitz determinants for Sakaguchi Classes},
  author = {Surya Giri and S. Sivaprasad Kumar},
  journal= {arXiv preprint arXiv:2210.13170},
  year   = {2022}
}
R2 v1 2026-06-28T04:21:03.183Z