This workshop aims at bringing together an interdisciplinary scientific community to share some of the state-of-the-art results in the theory of Herglotz-Nevanlinna functions, and to solve common open problems lying at the frontier of pure mathematics, applied mathematics, physics, and engineering. Further development of this theory would lead to significant progress not only in the area of pure mathematics, but also in its applications to antennas, metamaterials, and composite materials.