Behavior of Meromorphic Functions at the Boundary of the Unit Disc

Abstract

In this paper, a boundary version of the Schwarz lemma for meromorphic functions is investigated. The modulus of the angular derivative of the meromorphic function I-n f(z) = 1/z + 2(n)c(0) + 3(n)c(1)z+4(n)c(2)z(2) +... that belongs to the class of M on the boundary point of the unit disc has been estimated from below.