We investigate the conjugate indicator diagram or, equivalently, the indicator function of (frequently) hypercyclic functions of exponential type for differential operators. This gives insights into growth conditions for these functions on particular rays or sectors. Our research extends known results in several respects.

MSC 2010: 33E12, 30A10, 30D15, 30E15We consider some families of 3-index generalizations of the classical Mittag-Le²er functions and study the behaviour of these functions in domains of the complex plane. First, some inequalities in the complex plane and on its compact subsets are obtained. We also prove an asymptotic formula for the case of "large" values of the indices of these functions. Similar results have also been obtained by the author for the classical Bessel functions and their Wright's...

In this work we consider the Dunkl operator on the complex plane, defined by $${𝒟}_{k}f\left(z\right)=\frac{d}{dz}f\left(z\right)+k\frac{f\left(z\right)-f(-z)}{z},k\ge 0.$$ We define a convolution product associated with ${𝒟}_k$ denoted ${*}_k$ and we study the integro-differential-difference equations of the type $\mu {*}_{k}f={\sum }_{n=0}^{\infty }{a}_{n,k}{𝒟}_k^{n}f$, where $\left(a_{n,k}\right)$ is a sequence of complex numbers and $\mu$ is a measure over the real line. We show that many of these equations provide representations for particular classes of entire functions of exponential type.

We give a pure complex variable proof of a theorem by Ismail and Stanton and apply this result in the field of integer-valued entire functions. Our proof rests on a very general interpolation result for entire functions.

Étant donné une fonction $w\left(x\right)\ge 0$ paire et continue, on se demande si une fonction entière $\phi \left(z\right)\not\equiv 0$ de type exponentiel $a$ existe telle que $\phi \left(x\right)\exp w\left(x\right)$ soit borné pour $-\infty \<x\<\infty$. L’existence d’une telle $\phi$ est équivalente à celle d’une fonction croissante $\rho \left(t\right)$ sur $[0,\infty )$ telle que $\rho \left(t\right)=\theta \left(t\right)$, que $\frac{\rho \left(t\right)}{t}\to \frac{a}{\pi }$ pour $t\to \infty$, et que $w\left(x\right)+{\infty }_0^{\infty }log|1-\frac{x^2}{t^2}|d\rho \left(t\right)\le C^{\mathrm{te}}$, $x\in \mathbf{R}$, pourvu que $w\left(x\right)$ satisfasse à une condition de régularité assez peu restrictive, décrite au début de l’article. On démontre que l’existence d’une telle $\rho$ est à son tour équivalente à ce que la fonction $\frac{1}{\pi }{\int }_{-\infty }^{\infty }\frac{\left|\Im z\right|}{|z-t{|}^2}w\left(t\right)dt-a\left|\Im z\right|$ admette une majorante surharmonique...

Several representations of the space of Laplace ultradistributions supported by a half line are given. A strong version of the quasi-analyticity principle of Phragmén-Lindelöf type is derived.