Starlikeness of functions satisfying a differential inequality
Volume 61 / 1995
Annales Polonici Mathematici 61 (1995), 135-140
DOI: 10.4064/ap-61-2-135-140
Abstract
In a recent paper Fournier and Ruscheweyh established a theorem related to a certain functional. We extend their result differently, and then use it to obtain a precise upper bound on α so that for f analytic in |z| < 1, f(0) = f'(0) - 1 = 0 and satisfying Re{zf''(z)} > -λ, the function f is starlike.
