On some starlikeness conditions for analytic functions (Q1202801)

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scientific article; zbMATH DE number 109339
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On some starlikeness conditions for analytic functions
scientific article; zbMATH DE number 109339

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    On some starlikeness conditions for analytic functions (English)
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    22 February 1993
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    Let \(A(p)\) denote the class of functions \(f(z)=z^ p+\sum_{n=p+1}^ \infty a_ n z^ n\) which are analytic in the open unit disc \(E\) of the complex plane. \(f(z)\in A(p)\) is called \(p\)-valently starlike if \[ \text{Re}(zf'(z)/f(z))>0 \quad\text{in\;} E. \] In this paper the authors obtain results of the following type. If \(p\geq 2\) and \(f(z)\in A(p)\) satisfies \[ | \arg f^{(p)}(z)| < (3/4)\pi \] and \(f^{(p- 1)}(z)/z\) is typically real then \(f\) is \(p\)-valently starlike.
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    \(p\)-valently starlike
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