Abstract
Certain classes R(k)(mu, alpha); k >= 2, mu > -1, 0 <= alpha < 1 of analytic functions are defined in the unit disc using convolution technique. It is shown that functions in R(k)(mu, alpha) are of bounded radius rotation. Iris proved that R(k)(mu, alpha) and some other newly introduced related classes are invariant under the generalized Bernardi integral operator. The converse case as a radius problem is also considered. Theorems proved in this paper are best possible in some sense. (C) 2011 Elsevier Ltd. All rights reserved.