English

Sufficient conditions for strong starlikeness

Complex Variables 2020-07-07 v1

Abstract

Let pp be an analytic function defined on the open unit disc D\mathbb{D} with p(0)=1p(0)=1 and 0<α10< \alpha \leq 1. The conditions on complex valued functions CC, DD and EE are obtained for pp to be subordinate to ((1+z)/(1z))α((1+z)/(1-z))^{\alpha} when C(z)z2p(z)+D(z)zp(z)+E(z)p(z)=0C(z) z^{2}p''(z)+D(z)zp'(z) + E(z)p(z)=0. Sufficient conditions for confluent (Kummer) hypergeometric function and generalized and normalized Bessel function of the first kind of complex order to be subordinate to ((1+z)/(1z))α((1+z)/(1-z))^{\alpha} are obtained as applications. The conditions on α\alpha and β\beta are derived for pp to be subordinate to ((1+z)/(1z))α((1+z)/(1-z))^{\alpha} when 1+βzp(z)/pn(z)1+\beta zp'(z)/p^{n}(z) with n=1,2n=1,2 is subordinate to 1+4z/3+2z2/3=:φCAR(z)1+4z/3+2z^{2}/3=:\varphi_{CAR}(z). Similar problems were investigated for \REp(z)>0\RE p(z)>0 when the functions p(z)+βzp(z)/pn(z)p(z)+\beta zp'(z)/p^{n}(z) with n=0,2n=0,2 is subordinate to φCAR(z)\varphi_{CAR}(z). The condition on β\beta is determined for pp to be subordinate to ((1+z)/(1z))α((1+z)/(1-z))^{\alpha} when p(z)+βzp(z)/pn(z)p(z)+\beta zp'(z)/p^{n}(z) with n=0,1,2n=0,1,2 is subordinate to ((1+z)/(1z))α((1+z)/(1-z))^{\alpha}.

Keywords

Cite

@article{arxiv.2007.02877,
  title  = {Sufficient conditions for strong starlikeness},
  author = {Kanika Sharma and Nak Eun Cho and V. Ravichandran},
  journal= {arXiv preprint arXiv:2007.02877},
  year   = {2020}
}
R2 v1 2026-06-23T16:53:24.957Z