Browsing by Author "Kumar, Virendra"

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    Sharp Bounds on the Higher Order Schwarzian Derivatives for Janowski Classes
    (MDPI AG, 2018-08-18) Cho, Nak Eun; Kumar, Virendra; Ravichandran, V
    Higher order Schwarzian derivatives for normalized univalent functions were first considered by Schippers, and those of convex functions were considered by Dorff and Szynal. In the present investigation, higher order Schwarzian derivatives for the Janowski star-like and convex functions are considered, and sharp bounds for the first three consecutive derivatives are investigated. The results obtained in this paper generalize several existing results in this direction.
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    Starlike functions related to the bell numbers
    (MDPI AG, 2019-02-13) Cho, Nak Eun; Kumar, Sushil; Kumar, Virendra; Ravichandran, V; Srivastava, H. M.
    The present paper aims to establish the first order differential subordination relations between functions with a positive real part and starlike functions related to the Bell numbers. In addition, several sharp radii estimates for functions in the class of starlike functions associated with the Bell numbers are determined. © 2019 by the authors.