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In this article, we consider the family of functions $f$ analytic in the unit disk $|z|<1$ with the normalization $f(0)=0=f'(0)-1$ and satisfying the condition $\big |\big (z/f(z)\big )^{2}f'(z)-1\big |<\lambda $ for some $0<\lambda \leq…

Complex Variables · Mathematics 2021-04-13 Liulan Li , Saminathan Ponnusamy , Karl-Joachim Wirths

In this paper we give simple proofs for the main results concerning generalized Fekete-Szeg\H{o} functional of type $\left|a_{3}(f)-\lambda a_{2}(f)^{2}\right|-\mu|a_{2}(f)|$, where $\lambda\in\mathbb{C}$, $\mu>0$ and $a_{n}(f)$ is $n$-th…

Complex Variables · Mathematics 2024-12-31 Teodor Bulboacă , Milutin Obradović , Nikola Tuneski

Let $\mathcal{A}$ denote the class of analytic functions such that $f(0)=0$ and $f'(0)=1$ in the unit disk $\mathbb{D}:=\{z \in \mathbb{C}: |z|<1\}$. In this paper, we discuss the properties of a starlike subclass and compute its second and…

Complex Variables · Mathematics 2026-04-13 Vasudevarao Allu , Shobhit Kumar

Given a domain $\Omega$ in the complex plane $\mathbb{C}$ and a univalent function $q$ defined in an open unit disk $\mathbb{D}$ with nice boundary behaviour, Miller and Mocanu studied the class of admissible functions $\Psi(\Omega,q)$ so…

Complex Variables · Mathematics 2019-02-08 Adiba Naz , Sumit Nagpal , V. Ravichandran

In the present investigation, certain subclasses of close-to-convex functions are investigated. In particular, we obtain an estimate for the Fekete-Szeg\"o functional for functions belonging to the class, distortion, growth estimates and…

Complex Variables · Mathematics 2011-12-30 Nak Eun Cho , Oh Sang Kwon , V. Ravichandran

We prove two inequalities for the Mittag-Leffler function, namely that the function $\log E_\alpha(x^\alpha)$ is sub-additive for $0<\alpha<1,$ and super-additive for $\alpha>1.$ These assertions follow from two new binomial inequalities,…

Classical Analysis and ODEs · Mathematics 2021-12-16 Stefan Gerhold , Thomas Simon

Let $\phi$ be analytic and univalent ({\it i.e.,} one-to-one) in $\mathbb{D}:=\{z\in\mathbb{C}: |z|<1\}$ such that $\phi(\mathbb{D})$ has positive real part, is symmetric with respect to the real axis, starlike with respect to $\phi(0)=1,$…

Complex Variables · Mathematics 2026-04-15 Vasudevarao Allu , Himadri Halder

Let $\es$ be the family of analytic and univalent functions $f$ in the unit disk $\D$ with the normalization $f(0)=f'(0)-1=0$, and let $\gamma_n(f)=\gamma_n$ denote the logarithmic coefficients of $f\in {\es}$. In this paper, we study…

Complex Variables · Mathematics 2018-11-06 S. Ponnusamy , N. L. Sharma , K. -J. Wirths

In this paper we define a new subclass $\lambda$-bi-pseudo-starlike functions of $\Sigma$ related to shell-like curves connected with Fibonacci numbers and determine the initial Taylor-Maclaurin coefficients $|a_2|$ and $|a_3|$ for…

Complex Variables · Mathematics 2023-06-22 Kaliyappan Vijaya , Gangadharan Murugusundaramoorthy , Hatun Özlem Güney

A starlike function $f$ is characterized by the quantity $zf'(z)/f(z)$ lying in the right half-plane. This paper deals with sharp bounds for certain symmetric Toeplitz determinants whose entries are the coefficients of the functions $f$ for…

Complex Variables · Mathematics 2021-06-01 Om. P. Ahuja , Kanika Khatter , V. Ravichandran

This article presents several findings regarding second and third-order differential subordination of the form: $$ p(z)+\gamma_1 zp'(z)+\gamma_2 z^2p''(z)\prec h(z)\implies p(z)\prec e^z $$ and $$ p(z)+\gamma_1 zp'(z)+\gamma_2…

Complex Variables · Mathematics 2024-04-01 S. Sivaprasad Kumar , Neha Verma

Let $\mathcal{A}$ be the family of functions $f(z)=z+a_2z^2+...$ which are analytic in the open unit disc $\mathbb{D}=\{z: |z|<1 \}$, and denote by $\pe$ of functions $p(z)=z+p_1z+p_2z^2+...$ analytic in $\de$ such that $p(z)$ is in $\pe$…

Complex Variables · Mathematics 2017-05-04 Yaşar Polatoğlu , Yasemin Kahramaner , Arzu Yemişçi Şen

In this paper we study an interpolation problem involving the Fekete--Szeg\"{o} functional. It turns out that this problem links to the so-called filtration of infinitesimal generators. We introduce new filtration classes using the…

Complex Variables · Mathematics 2021-11-09 Mark Elin , Fiana Jacobzon , Nikola Tuneski

The logarithmic coefficients $\gamma_n$ of an analytic and univalent function $f$ in the unit disk $\mathbb{D}=\{z\in\mathbb{C}:|z|<1\}$ with the normalization $f(0)=0=f'(0)-1$ are defined by $\log \frac{f(z)}{z}= 2\sum_{n=1}^{\infty}…

Complex Variables · Mathematics 2016-08-25 Md. Firoz Ali , A. Vasudevarao

A typical quandary in geometric functions theory is to study a functional composed of amalgamations of the coefficients of the pristine function. Conventionally, there is a parameter over which the extremal value of the functional is…

Complex Variables · Mathematics 2018-09-19 P. Gochhayat , A. Prajapati , A. K. Sahoo

The symmetric decreasing rearrangement of functions on $\mathbb{R}^n$ features in several seminal inequalities, such as the P\'olya-Szeg\H{o} inequality. The latter was shown by the authors to hold for all smoothing rearrangements, a class…

Functional Analysis · Mathematics 2025-09-03 Gabriele Bianchi , Richard J. Gardner , Paolo Gronchi , Markus Kiderlen

Let $\mathcal{A}$ be the class of analytic functions $f$ in the unit disk $\mathbb{D}=\{z\in\mathbb{C}:|z|<1\}$ with the normalized conditions $f(0)=0$, $f'(0)=1$. For $-\pi/2<\alpha<\pi/2$ and $0\le \beta<1$, let…

Complex Variables · Mathematics 2023-09-27 Sanjit Pal

We will provide sufficient conditions for the shifted hypergeometric function $z_2F_1(a,b;c;z)$ to be a member of a specific subclass of starlike functions in terms of the complex parameters $a,b$ and $c.$ For example, we study starlikeness…

Complex Variables · Mathematics 2017-04-27 Toshiyuki Sugawa , Li-Mei Wang

Let $\mathcal{A}$ denote the class of analytic functions $f$ in the unit disk $\mathbb{D}=\{z\in\mathbb{C}:|z|<1\}$ normalized by $f(0)=0$, $f'(0)=1$. In the present article, we obtain the sharp estimates of the Schwarzian norm for…

Complex Variables · Mathematics 2022-12-14 Md Firoz Ali , Sanjit Pal

Let $\mathcal{U(\alpha, \lambda)}$, $0<\alpha <1$, $0 < \lambda <1$ be the class of functions $f(z)=z+a_{2}z^{2}+a_{3}z^{3}+\cdots$ satisfying $$\left|\left(\frac{z}{f(z)}\right)^{1+\alpha}f'(z)-1\right|<\lambda$$ in the unit disc ${\mathbb…

Complex Variables · Mathematics 2023-04-26 Milutin Obradović , Nikola Tuneski
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