Radius of strongly starlikeness for certain analytic functions (Q1607844)

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scientific article; zbMATH DE number 1780341
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Radius of strongly starlikeness for certain analytic functions
scientific article; zbMATH DE number 1780341

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    Radius of strongly starlikeness for certain analytic functions (English)
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    13 August 2002
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    The authors consider an interesting subclass of analytic and \(p\)-valent functions which are strongly starlike of order \(\gamma(p\in \mathbb{N}: =\{1,2,3,\dots\}\); \(0<\gamma\leq 1)\). In particular, for a normalized analytic and \(p\)-valent function \(f(z)\) in the open unit disk, they put \(F(z)=f(z) [Q(z)]^{\beta/n}\) \((\beta\in \mathbb{R};\;n\in\mathbb{N})\), where \(Q(z)\) is a polynomial of degree \(n\), all of whose zeros lie outside or on the unit circle, and then determine the radius \(R(\gamma)\) such that \(F(z)\) is \((p\)-valently) strongly starlike of order \(\gamma\) in \(|z|< R(\gamma)\).
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