Ding-Gong Yang

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Let S s (α) (0 ≤ α < 1/2) be the class of functions f (z) = z +··· which are analytic in the unit disk and satisfy there Re{zf (z)/(f (z) − f (−z))} > α. In the present paper, we find the sharp lower bound on Re{(f (z) − f (−z))/z} and investigate two subclasses S 0 (α) and T 0 (α) of S s (α). We derive sharp distortion inequalities and some properties of(More)
Let A p (p ∈ N) be the class of functions f (z) = z p + ∞ m=1 a p+m z p+m which are analytic in the unit disk. By virtue of the Ruscheweyh derivatives we introduce the new sub-classes C p (n, α, β, λ, µ) of A p. Subordination relations, inclusion relations, convolution properties and a sharp coefficient estimate are obtained. We also give a sufficient(More)