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This paper explores the asymptotic behaviour of the radii of convexity and uniform convexity for normalized Bessel functions with respect to large order. We provide detailed asymptotic expansions for these radii and establish recurrence…

Complex Variables · Mathematics 2025-10-17 Árpád Baricz , Pranav Kumar , Sanjeev Singh

In this investigation our main aim is to determine the radius of uniform convexity of the some normalized q-Bessel and Wright functions. Here we consider six different normalized forms of q-Bessel functions, while we apply three different…

Complex Variables · Mathematics 2019-06-27 İbrahim Aktaş , Evrim Toklu , Halit Orhan

The purpose of this paper is to give exact value of the radius of starlikeness and distortion theorem, Koebe domain for the class of Janowski's starlike functions of complex order. We note that the class of Janowski's starlike functions of…

Complex Variables · Mathematics 2007-05-23 Y. Polatoglu , M. Bolcal

In this study, a normalized form of regular Coulomb wave function is considered. By using differential subordination method due to Miller and Mocanu, we determine some conditions on the parameters such that the normalized regular Coulomb…

Complex Variables · Mathematics 2019-11-14 İbrahim Aktaş

Let -1\leq B<A\leq 1. Condition on \beta, is determined so that 1+\beta zp'(z)/p^k(z)\prec(1+Az)/(1+Bz)\;(-1<k\leq3) implies p(z)\prec \sqrt{1+z}. Similarly, condition on \beta is determined so that 1+\beta zp'(z)/p^n(z) or p(z)+\beta…

Complex Variables · Mathematics 2013-03-04 S. Sivaprasad Kumar , Virendra Kumar , V. Ravichandran , Nak Eun Cho

The primary objective of this work is to obtain some sufficient conditions so that normalized Gauss hypergeometric function satisfies exponential starlikeness and convexity in the unit disk. Moreover, conditions on parameter of this…

Complex Variables · Mathematics 2025-03-21 Anish Kumar , Sourav Das

Let $f=h+\overline{g}$ be a normalized harmonic mapping in the unit disk $\ID$. In this paper, we obtain the sharp radius of univalence, fully starlikeness and fully convexity of the harmonic linear differential operators…

Complex Variables · Mathematics 2017-08-15 ZhiHong Liu , Saminathan Ponnusamy

In this manuscript, we deal with three classes of quotient functions having fixed second coefficient described on open unit disk. The radius of strongly starlikeness, lemniscate starlikeness, lune starlikeness, parabolic starlikeness, sine…

Complex Variables · Mathematics 2022-03-17 Swati Anand , Naveen Kumar Jain , Sushil Kumar

Let $f(z)=z+\sum_{n=2}^{\infty}a_nz^n$ be analytic in the unit disk with second coefficient $a_2$ satisfying $|a_2|=2b$, $0\leq b\leq1$. Sharp radius of Janowski starlikeness and other radius constants are obtained when $|a_n|\leq cn+d$…

Complex Variables · Mathematics 2012-07-18 Rosihan M. Ali , Moradi Nargesi Mahnaz , V. Ravichandran

Geometric properties of the classical Lommel and Struve functions, both of the first kind, are studied. For each of them, there different normalizations are applied in such a way that the resulting functions are analytic in the unit disc of…

Classical Analysis and ODEs · Mathematics 2017-07-14 Árpád Baricz , Dimitar K. Dimitrov , Halit Orhan , Nihat Yagmur

The radii of convexity of some Lommel and Struve functions of the first kind are determined. For both of Lommel and Struve functions three different normalizations are applied in such a way that the resulting functions are analytic in the…

Classical Analysis and ODEs · Mathematics 2017-07-14 Árpád Baricz , Nihat Yağmur

We investigate certain properties of tilted (oblique) domains, associated with the Janowski function $(1+Az)/(1+Bz),$ where $A,B\in\mathbb{C}$ with $A\neq B$ and $|B|\leq 1$. We find several bounds for these oblique domains. Further, we…

Complex Variables · Mathematics 2021-04-20 S. Sivaprasad Kumar , Pooja Yadav

For $-1\leq B<A\leq 1$, let $\mathcal{S}^*(A,B)$ denote the class of Janowski starlike functions which satisfy the subordination relation $zf'(z)/f(z)\prec (1+Az)/(1+Bz)$. In the present article, we determine the sharp of pre-Schwarzian…

Complex Variables · Mathematics 2021-11-22 Md Firoz Ali , Sanjit Pal

A starlike univalent function $f$ is characterized by the function $zf'(z)/f(z)$; several subclasses of these functions were studied in the past by restricting the function $zf'(z)/f(z)$ to take values in a region $\Omega$ on the right-half…

Complex Variables · Mathematics 2021-01-06 Shalu Yadav , Kanika Sharma , V. Ravichandran

We introduce and study a class of starlike functions associated with the non-convex domain \[ \mathcal{S}^*_{nc} = \left\{ f \in \mathcal{A} : \frac{z f'(z)}{f(z)} \prec \frac{1+z}{\cos{z}} =: \varphi_{nc}(z), \;\; z \in \mathbb{D}…

Complex Variables · Mathematics 2024-12-09 S. Sivaprasad Kumar , Surya Giri

For $ -1 \leq B \leq 1$ and $A>B$, let $\mathcal{S}^*[A,B]$ denote the class of generalized Janowski starlike functions consisting of all normalized analytic functions $f$ defined by the subordination $z f'(z)/f(z) \prec (1+ A z)/(1+ B z)$…

Complex Variables · Mathematics 2017-03-13 V. Ravichandran , Shelly Verma

Let $\mathcal{S}^*_{Ne}$ be the collection of all analytic functions $f(z)$ defined on the open unit disk $\mathbb{D}$ and satisfying the normalizations $f(0)=f'(0)-1=0$ such that the quantity $zf'(z)/f(z)$ assumes values from the range of…

Complex Variables · Mathematics 2021-04-13 Lateef Ahmad Wani , A. Swaminathan

For the standard Ma-Minda class $\mathcal{S}^{*}(\psi)$ of univalent starlike functions, we derive $\mathcal{S}^{*}(\psi)$-radii for some well-known special functions. In addition, we obtain the set of extremal functions for the classical…

Complex Variables · Mathematics 2022-08-02 Kamaljeet Gangania , S. Sivaprasad Kumar

In the present investigation, we study the class of Sigmoid starlike functions, given by $\mathcal{S}^*_{SG}=\{f\in\mathcal{A}: {zf'(z)}/{f(z)}\prec 2/(1+e^{-z})\}$ in context of estimating the sharp radius constants associated with several…

Complex Variables · Mathematics 2022-08-03 Priyanka Goel , S. Sivaprasad Kumar

This paper introduce the Bessel-Struve kernel functions $\mathcal{B}_\nu$ defined on the unit disk in the complex plane. We studies the close-to-convexity of $\mathcal{B}_\nu$ with respect to several starlike functions. Sufficient condition…

Complex Variables · Mathematics 2016-02-01 Saiful R Mondal