Aktaş, Ibrahim; Toklu, Evrim; Orhan, Halit

In this investigation our main aim is to determine the radii of uniform convexity of selected normalized q -Bessel and Wright functions. Here we consider six different normalized forms of q -Bessel functions and we apply three different kinds of the normalization of the Wright function. We also show that the obtained radii are the smallest positive roots of some functional equations.

Aktaş, Ibrahim; Baricz, Árpád; Orhan, Halit

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 a combination of special functions, we obtain tight lower and upper bounds for the radii of starlikeness of these functions. By considering two different normalizations of Bessel and Struve functions we give some inequalities for the radii of convexity of the same functions. On the other hand, we show that the radii of univalence of some normalized Struve and Lommel functions are exactly the radii of starlikeness of the same functions. In addition, by using some ideas of Ismail and Muldoon we present some new lower and upper bounds for the zeros of derivatives of some normalized Struve and Lommel functions. The Laguerre-Pólya class of real entire functions plays an important role in our study.

Aktaş, Ibrahim; Orhan, Halit

In the present investigation our main aim is to give lower bounds for the ratio of some normalized q-Bessel functions and their sequences of partial sums. Especially, we consider Jackson's second and third q-Bessel functions and we apply one normalization for each of them.

Aktaş, Ibrahim; Baricz, Árpád; Yaǧmur, Nihat

Tight lower and upper bounds for the radii of univalence (and starlikeness) 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 functions is greater than the corresponding radius of univalence of Bessel functions. Moreover, by using the idea of Kreyszig and Todd, and Wilf it is proved that the radii of univalence of some normalized Struve and Lommel functions are exactly the radii of starlikeness of the same functions, and they are actually solutions of some functional equations. The Laguerre-Pólya class of entire functions plays an important role in our study.

Aktaş, Ibrahim; Orhan, Halit

In the present paper, we introduce a new subclass of functions which are analytic in the open unit disk. Also, we obtain coefficient inequalities for functions belonging to this class. Futhermore, we give some results associated with distortions bounds. In addition to that, we investigate lower bounds for partial sums of functions belonging to this class.

Aktaş, Ibrahim; Köse, Hasan

There are many relationships between the number theory and matrix theory. In this work, we defined two upper Hessenberg Matrices and then we showed that the permanents of these Hessenberg matrices are Pell-Lucas and Jacobsthal numbers.