AN IMPROVEMENT ON ESTIMATE OF d_0/d~* FOR STARLIKE FUNCTIONS

【摘要】： <正> Let S~* be the class of starlike functions in unit disc.For f∈S~*,denote its radiusof convexity by r_0 and let d_0=(?)|f(z)|,d~*=inf{|β||f(z)≠β,|z|1}.In this paper weprove d_0/d~*≥0.45,thus improving the result of d_0/d~*≥0.38 by McCarty,C.P.and Tepper,D.E.and d_0/d~*≥0.41 by Huang Xinzhong.