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Tight lower and upper bounds for the radius of univalence of some normalized Bessel, Struve and Lommel functions of the first kind are obtained via Euler-Rayleigh inequalities. It is shown also that the radius of univalence of the Struve…

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

The Bohr radius for a class $\mathcal{G}$ consisting of analytic functions $f(z)=\sum_{n=0}^{\infty}a_nz^n$ in unit disc $\mathbb{D}=\{z\in\mathbb{C}:|z|<1\}$ is the largest $r^*$ such that every function $f$ in the class $\mathcal{G}$…

Complex Variables · Mathematics 2020-07-21 Swati Anand , Naveen Kumar Jain , Sushil Kumar

In this paper our aim is to find the radii of starlikeness and convexity of the normalized Wright functions for three different kind of normalization. The key tools in the proof of our main results are the Mittag-Leffler expansion for…

Classical Analysis and ODEs · Mathematics 2021-01-19 Árpád Baricz , Evrim Toklu , Ekrem Kadıoğlu

In this paper our aim is to determine the radii of univalence, starlikeness and convexity of the normalized regular Coulomb wave functions for two different kinds of normalization. The key tools in the proof of our main results are the…

Complex Variables · Mathematics 2016-05-24 Árpád Baricz , Murat Çağlar , Erhan Deniz , Evrim Toklu

The main purpose of this paper is to determine the radii of starlikeness and convexity of the generalized $\emph{k}-$Bessel functions for three different kinds of normalization by using their Hadamard factorization in such a way that the…

Complex Variables · Mathematics 2019-03-06 Evrim Toklu

For an analytic function $f$ on the unit disk $\mathbb{D}=\{z:|z|<1\}$ satisfying $f(0)=0=f'(0)-1,$ we obtain sufficient conditions so that $f$ satisfies $|(zf'(z)/f(z))^2-1|<1.$ The technique of differential subordination of first or…

Complex Variables · Mathematics 2018-06-14 Vibha Madaan , Ajay Kumar , V. Ravichandran

Motivated by the pioneering work of M.S. Robertson [Ro54] and R.K. Brown [Br60], [Br62], who examined the geometric properties of some normalised solutions of second-order homogeneous differential equations, in this paper we investigate the…

Classical Analysis and ODEs · Mathematics 2025-10-16 Árpád Baricz , Pranav Kumar , Sanjeev Singh

In this paper we consider some normalized Bessel, Struve and Lommel functions of the first kind, and by using the Euler-Rayleigh inequalities for the first positive zeros of combination of special functions we obtain tight lower and upper…

Classical Analysis and ODEs · Mathematics 2021-01-19 İbrahim Aktaş , Árpád Baricz , Halit Orhan

This paper deals with connections on $p$-adic analytic curves, in the sense of Berkovich. The curves must be compact but the connections are allowed to have a finite number of meromorphic singularities on them. For any choice of a…

Algebraic Geometry · Mathematics 2010-03-30 Francesco Baldassarri

Let $\mathcal{G}(\alpha)$ denote the family of functions $ f(z)$ in the open unit disk $\mathbb D :=\{z\in\mathbb{C}: |z|<1\}$ that satisfy $ f(0)=0= f'(0)=1$ and \[\Re \left(1+ \dfrac{z f''(z)}{ f'(z)}\right)<1+\dfrac{\alpha}{2} , \quad…

Complex Variables · Mathematics 2024-06-27 Prachi Prajna Dash , Jugal Kishore Prajapat , Naveen Kumari

Concrete sharp constants in a pointwise estimate of the gradient of a harmonic function in the unit disk are obtained under the assumption that function belong to Hardy space $h^p$, $p\ge 1$. This generalizes some recent result of Maz'ya &…

Complex Variables · Mathematics 2011-04-06 David Kalaj , Marijan Markovic

There are a number of articles which deal with Bohr's phenomenon whereas only a few papers appeared in the literature on Rogosinski's radii for analytic functions defined on the unit disk $|z|<1$. In this article, we introduce and…

Complex Variables · Mathematics 2017-08-21 Ilgiz R Kayumov , Saminathan Ponnusamy

There is a universal constant $0<r_0<1$ with the following property. Suppose that $f$ is an analytic function on the unit disk $\D$, and suppose that there exists a constant $M>0$ so that the Euclidean area, counting multiplicity, of the…

Complex Variables · Mathematics 2007-05-23 Pietro Poggi-Corradini

The article discusses criteria for univalence of analytic functions in the unit disc. Various families of analytic functions depending on real parameters are considered. A unified method for creating new sets of conditions ensuring…

Complex Variables · Mathematics 2013-03-06 D. Aharonov , U. Elias

We consider fourth order ordinary differential operator with compactly supported coefficients on the line. We determine asymptotics of the number of resonances in complex discs at large radius. We consider resonances of an Euler-Bernoulli…

Mathematical Physics · Physics 2017-12-14 Andrey Badanin , Evgeny Korotyaev

We study radial behavior of harmonic functions in the unit disk belonging to the Korenblum class. We prove that functions which admit two-sided Korenblum estimate either oscillate or have slow growth along almost all radii.

Complex Variables · Mathematics 2012-09-20 Yurii Lyubarskii , Eugenia Malinnikova

In the field of radial basis functions mathematicians have been endeavouring to find infinitely differentiable and compactly supported radial functions. This kind of functions are extremely important for some reasons. First, its…

Numerical Analysis · Mathematics 2007-05-23 Lin-Tian Luh

In this note our aim is to determine the radius of starlikeness of the normalized Bessel functions of the first kind for three different kinds of normalization. The key tool in the proof of our main result is the Mittag-Leffler expansion…

Complex Variables · Mathematics 2014-04-23 Árpád Baricz , Pál A. Kupán , Róbert Szász

In this paper we deal with the radii of starlikeness and convexity of the $q-$Mittag--Leffler function for three different kinds of normalization by making use of their Hadamard factorization in such a way that the resulting functions are…

Complex Variables · Mathematics 2019-07-17 Evrim Toklu

There are many results for sufficient conditions of functions f(z) which are analytic in the open unit disc U to be starlike and convex in U. The object of the present paper is to derive some interesting sufficient conditions for f(z) to be…

Complex Variables · Mathematics 2013-03-05 Hitoshi Shiraishi , Shigeyoshi Owa