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Let $${\mathcal {S}}^*_s$$Ss∗ be the class of normalized analytic functions f defined on the unit disk such that the quantity $$zf'(z)/f(z)$$zf′(z)/f(z) lies in an eight-shaped region in the right-half plane,… Click to show full abstract
Let $${\mathcal {S}}^*_s$$Ss∗ be the class of normalized analytic functions f defined on the unit disk such that the quantity $$zf'(z)/f(z)$$zf′(z)/f(z) lies in an eight-shaped region in the right-half plane, which is the image of the unit disk under an entire function defined by $$\varphi (z)=1+\sin z$$φ(z)=1+sinz. For this class, we determine the $${\mathcal {S}}^*_s$$Ss∗-radii for the class of Janowski starlike functions and some other geometrically defined classes. A relation between this class and the class of Janowski starlike functions is also discussed.
Journal Title: Bulletin of the Iranian Mathematical Society
Year Published: 2019
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