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A certain subclass of analytic functions associated with operators of fractional calculus. (English) Zbl 0867.30015
Let $${\mathcal F} (n)$$ denote the class of functions of the form: $$f(z)=z+ \sum_{k=n +1}^\infty a_kz^k$$ $$(a_k\geq 0; n\in\mathbb{N})$$, which are analytic in the open unit disk. The authors consider the subclass $$S_{\lambda,\mu,\eta} (n,\sigma,\alpha)$$ of functions in $${\mathcal F} (n)$$ which also satisfy the following inequality: $\text{Re}\Bigl[\varphi_1 (\lambda,\mu,\eta) z^{\mu-1} \Bigl((1-\sigma) J_{0,z}^{\lambda, \mu,\eta} f(z)+\sigma zJ_{0,z}^{\lambda+1, \mu+1, \eta+1} f(z) \Bigr)\Bigr] >\alpha$
$(0\leq\lambda <1;\;0\leq\alpha <1;\;0\leq\sigma \leq 1;\;\mu,\eta\in \mathbb{R};\;\mu<2;\;\lambda- \eta<2;\;\mu-\eta<2),$ where $$\varphi_m (\lambda,\mu,\eta) =\Gamma(1-\mu+m) \Gamma(1+\eta- \lambda+m)/ \Gamma(1+m ) \Gamma(1+\eta- \mu+m)$$ and $$J_{0,z}^{\lambda, \mu,\eta}$$ is a certain fractional derivative operator defined in terms of the Gauss hypergeometric function $$_2F_1$$ [see H. M. Srivastava, M. Saigo and S. Owa, J. Math. Anal., Appl. 131, 412-420 (1988; Zbl 0628.30014)]. In this paper, some results connected with the new class $$S_{\lambda\mu,\eta} (n,\sigma,\alpha)$$ of functions, including the characterization property, the radii of close-to-convexity, starlikeness, convexity and distortion inequalities, are obtained.

MSC:
 30C45 Special classes of univalent and multivalent functions of one complex variable (starlike, convex, bounded rotation, etc.) 26A33 Fractional derivatives and integrals
Zbl 0628.30014
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References:
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