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This paper continues our investigation of the dynamics of families of transcendental meromorphic functions with finitely many singular values all of which are finite. Here we look at a generalization of the family of polynomials Pa(z) =zd−1(z−da/(d−1)), the family fλ=λtanpzq. These functions have a super-attractive fixed point, and, depending on p, one or two asymptotic values. Although many of the dynamical properties generalize, the existence of an essential singularity and of poles of multiplicity greater than one implies that significantly different techniques are required here. Adding transcendental methods to standard ones, we give a description of the dynamical properties; in particular we prove the Julia set of a hyperbolic map is either connected and locally connected or a Cantor set. We also give a description of the parameter plane of the family fλ. Again there are similarities to and differences from the parameter plane of the family Pa and again there are new techniques. In particular, we prove there is dense set of points on the boundaries of the hyperbolic components that are accessible along curves and we characterize these points.


This work is distributed under a CC-BY licence.

Originally published: Chen, Tao, and Linda Keen. "Dynamics of the Meromorphic Families fλ=λtanpzq." New Zealand Journal of Mathematics, vol. 52, 2021, pp. 469-510, doi:10.53733/135.



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