On a Class of Univalent Functions
نویسنده
چکیده
We consider the class of univalent functions f(z)= z+a3z3+a4z4+··· analytic in the unit disc and satisfying |(z2f ′(z)/f 2(z))−1|< 1, and show that such functions are starlike if they satisfy |(z2f ′(z)/f 2(z))−1|< (1/√2).
منابع مشابه
Certain Inequalities for a General Class of Analytic and Bi-univalent Functions
In this work, the subclass of the function class S of analytic and bi-univalent functions is defined and studied in the open unit disc. Estimates for initial coefficients of Taylor- Maclaurin series of bi-univalent functions belonging these class are obtained. By choosing the special values for parameters and functions it is shown that the class reduces to several earlier known classes of analy...
متن کاملThe Fekete-Szegö problem for a general class of bi-univalent functions satisfying subordinate conditions
In this work, we obtain the Fekete-Szegö inequalities for the class $P_{Sigma }left( lambda ,phi right) $ of bi-univalent functions. The results presented in this paper improve the recent work of Prema and Keerthi [11].
متن کاملCoefficient bounds for a new class of univalent functions involving Salagean operator and the modified Sigmoid function
We define a new subclass of univalent function based on Salagean differential operator and obtained the initial Taylor coefficients using the techniques of Briot-Bouquet differential subordination in association with the modified sigmoid function. Further we obtain the classical Fekete-Szego inequality results.
متن کاملCertain subclasses of bi-univalent functions associated with the Aghalary-Ebadian-Wang operator
In this paper, we introduce and investigate two new subclasses of the functions class $ Sigma $ of bi-univalent functions defined in the open unit disk, which are associated with the Aghalary-Ebadian-Wang operator. We estimate the coefficients $|a_{2} |$ and $|a_{3} |$ for functions in these new subclasses. Several consequences of the result are also pointed out.
متن کاملIdentification of Initial Taylor-Maclaurin Coefficients for Generalized Subclasses of Bi-Univalent Functions
In the present work, the author determines some coefficient bounds for functions in a new class of analytic and bi-univalent functions, which are introduced by using of polylogarithmic functions. The presented results in this paper one the generalization of the recent works of Srivastava et al. [26], Frasin and Aouf [13] and Siregar and Darus [25].
متن کاملSandwich-type theorems for a class of integral operators with special properties
In the present paper, we prove subordination, superordination and sandwich-type properties of a certain integral operators for univalent functions on open unit disc, moreover the special behavior of this class is investigated.
متن کامل