Research Article
Starlikeness Associated with Tangent Hyperbolic Function
Huo Tang,
1
Muhammad Arif ,
2
Khalil Ullah,
2
Nazar Khan ,
3
Mirajul Haq,
2
and Bilal Khan
4
1
School of Mathematics and Computer Sciences, Chifeng University, Chifeng, 024000 Inner Mongolia, China
2
Department of Mathematics, Abdul Wali Khan University, Mardan 23200, Pakistan
3
Department of Mathematics, Abbottabad University of Science and Technology, Abbottabad, Pakistan
4
School of Mathematical Sciences and Shanghai Key Laboratory of PMMP, East China Normal University, 500 Dongchuan Road,
Shanghai 200241, China
Correspondence should be addressed to Nazar Khan; nazarmaths@gmail.com
Received 18 March 2022; Accepted 20 April 2022; Published 20 May 2022
Academic Editor: Adel A. Attiya
Copyright © 2022 Huo Tang et al. This is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
The primary objective of this study is to establish a class of starlike functions (symmetric under rotation) that are related to a
tangent hyperbolic. Integral preserving properties along with the sufficiency criteria involving coefficients are investigated for
the same class. Differential subordinations problems, which are linked to Janowski and tangent hyperbolic functions, are also
discussed. We also utilize these findings to find sufficient conditions for the starlike functions.
1. Introduction and Motivations
The purpose of this portion is to provide certain fundamental
ideas in geometric function theory that will assist in the
understanding of our results. In this respect, we start by
defining the most fundamental class A , which contains func-
tions that are holomorphic or regular or analytic in the subset
D = fz : jzj <1g of the complex numbers ℂ, as follows
A = g : g is regular in D with gz ðÞ = z + 〠
∞
n=2
a
n
z
n
( )
: ð1Þ
Also, the subset set A ⊂ S comprises all normalised
univalent functions in D. For the given functions g
1
, g
2
∈ A , we say that g
1
is subordinate to g
2
, written appropri-
ately as g
1
≺ g
2
, if there exist a Schwarz function w, which
is holomorphic in D with
w 0 ðÞ = 0 and wz ðÞ j j < 1, ð2Þ
so that
g
1
z ðÞ = g
2
wz ðÞ ð Þ, z ∈ D ð Þ: ð3Þ
Second, if g
2
in D is univalent, then, the following equiv-
alence holds true:
g
1
≺ g
2
⟸ g
1
0 ðÞ = g
2
0 ðÞ and g
1
D ð Þ ⊂ g
2
D ð Þ: ð4Þ
In the analysis of holomorphic functions, image domains
are extremely important. Based on the geometry of image
domains, holomorphic functions are divided into various
classes. Ma and Minda [1] proposed an analytic function ϕ
ðReϕ > 0inDÞ in 1992, which is normalised by representa-
tions ϕð0Þ =1 and ϕ
′
ð0Þ >0. Also, the region ϕðDÞ is a
star-shaped about 1 and is symmetric on the real line axis.
Particularly,
(i) If we take
ϕ z ðÞ =
1+ Az
1+ Bz
−1 ≦ B < A ≦ 1 ð Þ, ð5Þ
then, we achieve the class given by
S
∗
A, B ½ ≡ S
∗
1+ Az
1+ Bz
, ð6Þ
Hindawi
Journal of Function Spaces
Volume 2022, Article ID 8379847, 14 pages
https://doi.org/10.1155/2022/8379847