Computing iterative roots of polygonal functions

Based on the iterative root theory for monotone functions, an algorithm for computing polygonal iterative roots of increasing polygonal functions was given by J. Kobza. In this paper we not only give an algorithm for roots of decreasing polygonal functions but also generalize Kobzaʹs results to the general n. Furthermore, we extend our algorithms for polygonal PM functions, a class of non-monotonic functions.