Subclasses of Multivalent Harmonic Mappings Defined by Convolution

A new subclass of multivalent harmonic functions defined by convolution is introduced in this paper. The subclass generates known subclasses of multivalent harmonic functions, and thus provides a unified treatment in the study of these subclasses. Sufficient coefficient conditions are obtained that are also shown to be necessary when the functions have negative coefficients. Growth estimates and extreme points are also determined. In addition conditions for starlikeness of the Dziok-Srivastava linear operator involving the generalized hypergeometric functions are discussed.