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Abstract. For n ≥ 1, let A denote the class of all analytic functions f in the unit disk ∆ of the form f (z) = z + ∞ k=2 a k z k . For Re α < 2 and γ > 0 given, let P(γ, α) denote the class of all functions f ∈ A satisfying the conditionWe find sufficient conditions for functions in P(γ, α) to be starlike of order β. A generalization of this result along with some convolution results is also obtained.

Abstract. Let A denote the class of all normalized analytic functions f (f (0) = 0 = f (0) − 1) in the open unit disc ∆. For 0 < λ ≤ 1, defineRecently, the problem of finding the starlikeness of these classes has been considered by Obradović and Ponnusamy, and later by Obradović et al. In this paper, the authors consider the problem of finding the order of starlikeness and of convexity of U (λ) and P(2λ), respectively. In particular, for f ∈ A with f (0) = 0, we find conditions on λ, β * (λ) and β(λ) so that U (λ) S * (β * (λ)) and P(2λ) K(β(λ)). Here, S * (β) and K(β) (β < 1) denote the classes of functions in A that are starlike of order β and convex of order β, respectively. In addition to these results, we also provide a coefficient condition for functions to be in K(β). Finally, we propose a conjecture that each function f ∈ U (λ) with f (0) = 0 is convex at least when 0 < λ ≤ 3 − 2 √ 2.

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