C. Cassisa, P. E. Ricci, I. Tavkhelidze

Operational Identities for Circular and Hyperbolic Functions and Their Generalizations

Starting from the exponential, some classes of analytic functions of the derivative operator are studied, including pseudo-hyperbolic and pseudo-circular functions. Some formulas related to operational
calculus are deduced, and the important role played in such a context by Hermite-Kampé de Fériet polynomials is underlined.