Radius Constants of Sigmoid Starlike Functions

In the present investigation, we study the class of Sigmoid starlike functions, given by ${\mathcal{S}}_{SG}^{\ast }=\{f\in \mathcal{A}:z{f}^{\mathrm{\prime }}(z)\mathrm{/}f(z)\prec 2\mathrm{/}(1+e^{-z})\}$ in context of estimating the sharp radius constants associated with several known subclasses of starlike functions. Further, graphical validation for the sharpness of results is also provided.