Some sufficient conditions on certain constants which are involved in some first and second-order differential subordinations associated with functions positive real part like modified Sigmoid function, exponential function Janowski obtained so that the analytic [Formula: see text] normalized by condition text], is subordinate to function. The admissibility for used as a tool proof of results. ...

This paper aims to provide sufficient conditions for starlikeness and convexity of Hadamard product (convolution) certain multivalent analytic functions with positive real parts. Moreover, the a integral operator other convolution results are also considered.

The purpose of this note is to develop facts about positive real transfer functions for discretetime linear systems, i.e., in the z plane. Positive real functions arise naturally as the impedance functions of passive continuous-time systems.

A natural interpolation problem in the cone of positive harmonic functions is considered and the corresponding interpolating sequences are geometrically described.

Let H be any complex inner product space with inner product < ·, · >. We say that f : | C → | C is Hermitian positive definite on H if the matrix ( f(< z,z >) )n r,s=1 (∗) is Hermitian positive definite for all choice of z, . . . ,z in H, all n. It is strictly Hermitian positive definite if the matrix (∗) is also non-singular for any choice of distinct z, . . . ,z in H. In this article we prove...

Examples of positive recurrent functions Pawel Hanus and Mariusz Urba nski Department of Mathematics, University of North Texas, Denton, TX 76203-5118, USA e-mail: [email protected] Abstract. In [Sa] Sarig has introduced and explored the concept of positively recurrent functions. In this paper we construct a natural wide class of such functions and we show that they have stronger p...