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TÜBİTAK

Journal

2019

Analytic function

Articles 1 - 3 of 3

Full-Text Articles in Physical Sciences and Mathematics

Properties Of A Generalized Class Of Analytic Functions With Coefficient Inequality, Ben Wongsaijai, Nattakorn Sukantamala Jan 2019

Properties Of A Generalized Class Of Analytic Functions With Coefficient Inequality, Ben Wongsaijai, Nattakorn Sukantamala

Turkish Journal of Mathematics

Let $(\beta_n)_{n\ge 2}$ be a sequence of nonnegative real numbers and $\delta$ be a positive real number. We introduce the subclass $\mathcal{A}(\beta_n,\delta)$ of analytic functions, with the property that the Taylor coefficients of the function $f$ satisfies $\sum_{n\ge2}^{\infty}\beta_n a_n \le \delta$, where $f(z)=z+\sum_{n=2}^{\infty}a_nz^n$. The class $\mathcal{A}(\beta_n,\delta)$ contains nonunivalent functions for some choices of $(\beta_n)_{n\ge 2}$. In this paper, we provide some general properties of functions belonging to the class $\mathcal{A}(\beta_n,\delta)$, such as the radii of univalence, distortion theorem, and invariant property. Furthermore, we derive the best approximation of an analytic function in such class by using the semiinfinite quadratic programming. …


Notes On Certain Analytic Functions, Emel Yavuz Duman, Shigeyoshi Owa Jan 2019

Notes On Certain Analytic Functions, Emel Yavuz Duman, Shigeyoshi Owa

Turkish Journal of Mathematics

Let $\mathcal{A}(n)$ be the class of functions $$f(z)=a_nz^n + a_{n+1}z^{n+1}+\cdots (n\in \mathbb{N}),$$ which are analytic in the open unit disk $\mathbb{U}$, where $a_n \neq 0$. For $f(z)\in \mathcal{A}(n)$, Miller and Mocanu in 1978 showed a very interesting result for $f(z)$. Applying the result due to Miller and Mocanu, we would like to consider some new results for such functions. Our results in this paper are generalizations for results by Nunokawa in 1992.


Coefficient Estimates For A New Subclasses Of Λ-Pseudo Biunivalent Functions Withrespect To Symmetrical Points Associated With The Horadam Polynomials, Adnan Alamoush Jan 2019

Coefficient Estimates For A New Subclasses Of Λ-Pseudo Biunivalent Functions Withrespect To Symmetrical Points Associated With The Horadam Polynomials, Adnan Alamoush

Turkish Journal of Mathematics

In the present article, we introduce two new subclasses of λ-pseudo biunivalent functions with respect to symmetrical points in the open unit disk U defined by means of the Horadam polynomials. For functions belonging to these subclasses, estimates on the Taylor -Maclaurin coefficients ja2j and ja3j are obtained. Fekete-Szegö inequalities of functions belonging to these subclasses are also founded. Furthermore, we point out several new special cases of our results.