BEHAVIOR OF HOLOMORPHIC FUNCTIONS ON THE BOUNDARY OF THE UNIT DISC

Abstract

In this paper, we establish lower estimates for the modulus of the non tangential derivative of the holomorphic function f (z) at the boundary of the unit disc. Also, we shall give an estimate below vertical bar f ''(b)vertical bar according to the first nonzero Taylor coefficient of about two zeros, namely z = 0 and z(0) not equal 0.