Coefficient Problems for Subclasses of Close-to-Star Functions

摘要

In this paper, two subclasses of close-to-star functions and two subclasses of close-to-convex functions are studied. By using the coefficient estimates of the known Carathe ' odory function classes, the upper bounds of the Zalcman functional J(3;4), Hankel determinant H-2(3) and Toeplitz determinant of given function classes are estimated. Some sharp results are obtained.