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A normalized analytic function f is shown to be univalent in the open unit disk D if its second coefficient is sufficiently small and relates to its Schwarzian derivative through a certain inequality. New criteria for analytic functions to…

Complex Variables · Mathematics 2011-08-30 Rosihan M. Ali , Mahnaz M. Nargesi , V. Ravichandran , A. Swaminathan

In this paper, we introduce a family of analytic functions given by $$\psi_{A,B}(z):= \dfrac{1}{A-B}\log{\dfrac{1+Az}{1+Bz}},$$ which maps univalently the unit disk onto either elliptical or strip domains, where either $A=-B=\alpha$ or…

Complex Variables · Mathematics 2022-09-12 S. Sivaprasad Kumar , Pooja Yadav

In this paper, we introduce and investigate a new subclass of the function class $\Sigma$ of bi-univalent functions defined in the open unit disk, which are associated with the S\u{a}l\u{a}gean type $q-$ difference operator and satisfy some…

Complex Variables · Mathematics 2017-10-03 G. Murugusundaramoorthy , K. Vijaya

In the present paper we introduce and investigate an interesting subclass K_{s}^{(k)}({\gamma},p) of analytic and p-valently close-to-convex functions in the open unit disk U. For functions belonging to this class, we derive several…

Complex Variables · Mathematics 2016-12-28 Serap Bulut

We consider functions of the type $f(z)=z+a_2z^2+a_3z^3+\cdots$ from a family of all analytic and univalent functions in the unit disk. Let $F$ be the inverse function of $f$, given by $F(z)=w+\sum_{n=2}^{\infty}A_nw^n$ defined on some…

Complex Variables · Mathematics 2021-11-02 Vasudevarao Allu , Vibhuti Arora

The aim of this paper is to define a new operator by using the generalized Struve functions. By using this operator we define a subclass of analytic functions. We discuss some properties of this class such as inclusion problems, radius…

Complex Variables · Mathematics 2015-02-18 Mohsan Raza , Nihat Yağmur

For $0<\lambda\le 1$, let $\mathcal{U}(\lambda)$ be the class analytic functions $f(z)= z+\sum_{n=2}^{\infty}a_n z^n$ in the unit disk $\mathbb{D}$ satisfying $|f'(z)(z/f(z))^2-1|<\lambda$ and $\mathcal{U}:=\mathcal{U}(1)$. In the present…

Complex Variables · Mathematics 2020-06-30 Md Firoz Ali , Vasudevarao Allu , Hiroshi Yanagihara

Let $\mathcal{A}$ denote the class of analytic functions $f$ on the unit disc $\mathbb{D}=\{z\in\mathbb{C}:\;|z|<1\}$ normalized by $f(0)=0$ and $f^{\prime}(0)=1$. In the present article, we consider and $\mathcal{F}(c)$ the subclasses of…

Complex Variables · Mathematics 2025-06-26 Molla Basir Ahamed , Rajesh Hossain , Sabir Ahammed

In this paper we study functions $ \omega(z) = c_1z+c_2z^2+c_3z^3+\cdots$ analytic in the open unit disk ${\mathbb D}$ and such that $|\omega'(z)|\le1$ for all $z\in{\mathbb D}$. For these functions we give estimates (sometimes sharp) for…

Complex Variables · Mathematics 2023-11-14 Milutin Obradovic , Nikola Tuneski

Let ${\mathcal A}$ be the class of functions $f$ that are analytic in the unit disk ${\mathbb D}$ and normalized such that $f(z)=z+a_2z^2+a_3z^3+\cdots$. Let $0<\lambda\le1$ and \[ {\mathcal U}(\lambda) = \left\{ f\in{\mathcal A}: \left…

Complex Variables · Mathematics 2021-04-26 Milutin Obradović , Nikola Tuneski

We consider three classes of functions defined using the class $\mathcal{P}$ of all analytic functions $p(z)=1+cz+\dotsb$ on the open unit disk having positive real part and study several radius problems for these classes. The first class…

Complex Variables · Mathematics 2020-07-21 Adam Lecko , V. Ravichandran , Asha Sebastian

Let $\mathcal{H}$ be the class of harmonic functions $f=h+\overline{g}$ in the unit disk $\mathbb{D}:=\{z\in\mathbb{C}:|z|<1\}$, where $h$ and $g$ are analytic in $\mathbb{D}$ with the normalization $h(0)=g(0)=h'(0)-1=0$. Let…

Complex Variables · Mathematics 2026-04-14 Raju Biswas

We investigate the non-univalent function's properties reminiscent of the theory of univalent starlike functions. Let the analytic function $\psi(z)=\sum_{i=1}^{\infty}A_i z^i$, $A_1\neq0$ be univalent in the unit disk. Non-univalent…

Complex Variables · Mathematics 2022-08-02 Kamaljeet Gangania

In this study, a subclass of an univalent function with negative coefficients which is defined by a new general Linear operator have been introduced. The sharp results for coefficients estimators, distortion and closure bounds, Hadamard…

Complex Variables · Mathematics 2020-05-15 Mazin Sh. Mahmoud , Abdul Rahman S. Juma , Raheam A. Mansor Al-Saphory

In this paper, we introduce a new subclass of harmonic functions $f=s+\overline{t}$ in the open unit disk $U =\left \{ z\in C:\left \vert z\right \vert <1\right \} $ satisfying ${\text{Re}}\left[ \gamma s^{\prime }(z)+\delta zs^{\prime…

Complex Variables · Mathematics 2021-07-09 Serkan Çakmak , Elif Yaşar , Sibel Yalçın

In the present investigation, we consider two new subclasses N_{{\Sigma}}^{{\mu}}({\alpha},{\lambda}) and N_{{\Sigma}}^{{\mu}}({\beta},{\lambda}) of bi-univalent functions defined in the open unit disk U={z:|z|<1}. Besides, we find upper…

Complex Variables · Mathematics 2012-04-20 Murat Çağlar , Halit Orhan , Nihat Yağmur

We introduce a class of analytic functions subordinate to the function $1+\sinh \left( z\right) $ and obtain various necessary and sufficient conditions for functions to be in the class. These conditions mainly comprise of the coefficient…

Complex Variables · Mathematics 2020-11-11 S. Sivaprasad Kumar , Muhammad Ghaffar Khan , Bakhtiar Ahmad , Wali Khan Mashwani

In this paper we introduce and investigate two new subclasses of the function class $\Sigma$ of bi-univalent functions of complex order defined in the open unit disk, which are associated with the Hohlov operator, and satisfying subordinate…

Complex Variables · Mathematics 2016-07-29 T. Bulboacă , G. Murugusundaramoorthy

For an analytic function $f(z)$ on the unit disk $|z|<1$ with $f(0)=f'(0)-1=0$ and $f(z)\ne0, 0<|z|<1,$ we consider the power deformation $f_c(z)=z(f(z)/z)^c$ for a complex number $c.$ We determine those values $c$ for which the operator…

Complex Variables · Mathematics 2011-01-21 Yong Chan Kim , Toshiyuki Sugawa

Let function $f$ be analytic in the unit disk ${\mathbb D}$ and be normalized so that $f(z)=z+a_2z^2+a_3z^3+\cdots$. In this paper we give sharp bounds of the modulus of its second, third and fourth coefficient, if $f$ satisfies \[…

Complex Variables · Mathematics 2018-10-15 Milutin Obradovic , Nikola Tuneski