Research Article Fekete-Szeg Inequality for a Subclass of -Valent Analytic Functions

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Hindawi Publishing Corporation
Journal of Applied Mathematics
Volume 2013, Article ID 127615, 7 pages
http://dx.doi.org/10.1155/2013/127615
Research Article
Fekete-Szegy Inequality for a Subclass of
𝑝-Valent Analytic Functions
Mohsan Raza,1 Muhammad Arif,2 and Maslina Darus3
1
Department of Mathematics, Government College University Faisalabad, Faisalabad, Punjab 38000, Pakistan
Department of Mathematics, Abdul Wali Khan University Mardan, Mardan, Khyber Pakhtunkhwa 23200, Pakistan
3
School of Mathematical Sciences, Faculty of Science and Technology Universiti Kebangsaan Malaysia, 43600 Bangi,
Selangor D. Ehsan, Malaysia
2
Correspondence should be addressed to Muhammad Arif; marifmaths@yahoo.com
Received 18 January 2013; Accepted 11 April 2013
Academic Editor: Mina Abd-El-Malek
Copyright © 2013 Mohsan Raza 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 main object of this paper is to study Fekete-SzegoΜ‹ problem for the class of 𝑝-valent functions. Fekete-SzegoΜ‹ inequality of several
classes is obtained as special cases from our results. Applications of the results are also obtained on the class defined by convolution.
1. Introduction and Preliminaries
Let 𝐴 𝑝 denote the class of functions 𝑓(𝑧) of the form
∞
𝑓 (𝑧) = 𝑧𝑝 + ∑ π‘Žπ‘› 𝑧𝑛 ,
(𝑝 ∈ N = {1, 2, 3, . . .}) ,
𝑛=𝑝+1
(1)
which are analytic in the open unit disk 𝐸. Also, 𝐴 1 = 𝐴, the
usual class of analytic functions defined in the open unit disk
𝐸 = {𝑧 : |𝑧| < 1}. Let 𝑓(𝑧) and 𝑔(𝑧) be analytic in 𝐸. We say
that the function 𝑓 is subordinate to the function 𝑔 and write
𝑓(𝑧) β‰Ί 𝑔(𝑧), if and only if there exists Schwarz function 𝑀,
analytic in 𝐸 such that 𝑀(0) = 0, |𝑀(𝑧)| < 1 for 𝑧 ∈ 𝐸, and
𝑓(𝑧) = 𝑔(𝑀(𝑧)). In particular, if 𝑔 is univalent in 𝐸, then we
have the following equivalence:
𝑓 (𝑧) β‰Ί 𝑔 (𝑧) ⇐⇒ 𝑓 (0) = 𝑔 (0) ,
𝑓 (𝐸) ⊂ 𝑔 (𝐸) .
(2)
For any two analytic functions 𝑓(𝑧) of the form (1) and
𝑔(𝑧) with
𝑧𝑓󸀠 (𝑧)
β‰Ί πœ™ (𝑧) ,
𝑝𝑓 (𝑧)
𝑧 ∈ 𝐸.
(5)
The class 𝑆𝑝∗ (πœ™) was defined and studied by Ali et al. [1]. They
obtained the Fekete-SzegoΜ‹ inequality for functions in the class
𝑆𝑝∗ (πœ™). The class 𝑆1∗ (πœ™) coincides with the class 𝑆∗ (πœ™) discussed
by Ma and Minda [2]. Owa [3] introduced a subclass of 𝑝valently Bazilevic functions 𝐻𝑝 (𝐴, 𝐡, 𝛼, 𝛽). A function 𝑓 ∈
𝐴 𝑝 is said to be in the class 𝐻𝑝 (𝐴, 𝐡, 𝛼, 𝛽) if and only if
(1 − 𝛽) (
𝑓(𝑧) 𝛼
𝑧𝑓󸀠 (𝑧) 𝑓 (𝑧) 𝛼 1 + 𝐴𝑧
+
𝛽
,
)
) β‰Ί
(
𝑧𝑝
𝑝𝑓 (𝑧) 𝑧𝑝
1 + 𝐡𝑧
𝑧 ∈ 𝐸,
(6)
∞
𝑔 (𝑧) = 𝑧𝑝 + ∑ 𝑏𝑛 𝑧𝑛 ,
𝑧 ∈ 𝐸,
𝑛=𝑝+1
(3)
the convolution (Hadamard product) is given by
𝑝
Let πœ™(𝑧) be an analytic function with positive real part on 𝐸
with πœ™(0) = 1, πœ™σΈ€  (0) > 0, which maps the unit disk 𝐸 onto
a region starlike with respect to 1 which is symmetric with
respect to the real axis. Denote by 𝑆𝑝∗ (πœ™) the class of functions
𝑓 analytic in 𝐸 for which
∞
𝑛
(𝑓 ∗ 𝑔) (𝑧) = 𝑧 + ∑ π‘Žπ‘› 𝑏𝑛 𝑧 ,
𝑛=𝑝+1
𝑧 ∈ 𝐸.
(4)
where −1 ≤ 𝐡 < 𝐴 ≤ 1, 𝛼 ≥ 0, and 0 ≤ 𝛽 ≤ 1. We now define
the following subclass of analytic functions.
Definition 1. Let πœ™(𝑧) be a univalent starlike function with
respect to 1 which maps the unit disk 𝐸 onto a region in the
right half-plane which is symmetric with respect to the real
2
Journal of Applied Mathematics
axis with πœ™(0) = 1 and πœ™σΈ€  (0) > 0. A function 𝑓 ∈ 𝐴 𝑝 is in the
class 𝑉𝑝,𝑏,𝛼,𝛽 (πœ™) if
1−
𝛼
𝑓 (𝑧)
2 2
+ { (1 − 𝛽) ( 𝑝 )
𝑏 𝑏
𝑧
𝑧𝑓󸀠 (𝑧) 𝑓 (𝑧) 𝛼
+𝛽
) } β‰Ί πœ™ (𝑧) ,
(
𝑝𝑓 (𝑧) 𝑧𝑝
We need the following results to obtain our main results.
Lemma 3 (see [1]). Let Ω be the class of analytic functions 𝑀,
normalized by 𝑀(0) = 0, satisfying condition |𝑀(𝑧)| < 1. If 𝑀 ∈
Ω and 𝑀(𝑧) = 𝑀1 𝑧 + 𝑀2 𝑧2 + ⋅ ⋅ ⋅ , 𝑧 ∈ 𝐸, then
(7)
−𝑑,
{
{
󡄨󡄨
2 󡄨󡄨
󡄨󡄨𝑀2 − 𝑑𝑀1 󡄨󡄨 ≤ {1,
󡄨 {
󡄨
{𝑑,
where 0 ≤ 𝛽 ≤ 1, 𝛼 ≥ 0, and 𝑏 > 0.
Definition 2. A function 𝑓 ∈ 𝐴 𝑝 is in the class 𝑉𝑝,𝑏,𝛼,𝛽,𝑔 (πœ™) if
𝛼
(𝑓 ∗ 𝑔) (𝑧)
2 2
)
1 − + { (1 − 𝛽) (
𝑏 𝑏
𝑧𝑝
σΈ€ 
+𝛽
𝛼
𝑧(𝑓 ∗ 𝑔) (𝑧) (𝑓 ∗ 𝑔) (𝑧)
(
) } β‰Ί πœ™ (𝑧) ,
𝑧𝑝
𝑝 (𝑓 ∗ 𝑔) (𝑧)
(8)
where 0 ≤ 𝛽 ≤ 1, 𝛼 ≥ 0, and 𝑏 > 0. In other words, a function 𝑓 ∈ 𝐴 𝑝 is in the class 𝑉𝑝,𝑏,𝛼,𝛽,𝑔 (πœ™) if (𝑓 ∗ 𝑔)(𝑧) ∈
𝑉𝑝,𝑏,𝛼,𝛽 (πœ™).
We have the following special cases.
(i) 𝑉𝑝,2,1,1 (πœ™) coincides with the class
and studied by Ali et al. [1].
𝑆𝑝∗ (πœ™) introduced
(ii) For 𝑝 = 1, 𝑏 = 2, and 𝛽 = 1, we have the class 𝐡𝛼 (πœ™)
introduced and studied by Ravichandran et al. [4].
(iii) For 𝑏 = 2 and πœ™(𝑧) = (1 + 𝐴𝑧)/(1 + 𝐡𝑧), the class
𝑉𝑝,2,𝛼,𝛽 (πœ™) reduces to 𝐻𝑝 (𝐴, 𝐡, 𝛼, 𝛽) introduced and
studied by Owa [3].
(iv) For πœ™(𝑧) = (1 + (1 − 2𝛾)𝑧)/(1 − 𝑧), the class 𝑉𝑝,2,𝛼,1 (πœ™)
reduces to the class 𝐡𝑝 (𝛼, 𝛾) defined as
𝑧𝑓 (𝑧) 𝑓 (𝑧)
) ) > 𝛾,
𝐡𝑝 (𝛼, 𝛾) = {𝑓 ∈ 𝐴 𝑝 : Re (
(
𝑝𝑓 (𝑧) 𝑧𝑝
(9)
(v) For πœ™(𝑧) = (1 + (1 − 2𝛾)𝑧)/(1 − 𝑧), the class 𝑉𝑝,2,𝛼,0 (πœ™)
is defined as
𝑓 (𝑧) 𝛼
) > 𝛾, 0 ≤ 𝛾 < 1, 𝑧 ∈ 𝐸} .
𝑧𝑝
(10)
(vi) 𝑉1,2,0,1 (πœ™) = 𝑆∗ (πœ™) is investigated by Ma and Minda
[2].
(vii) For πœ™(𝑧) = (1 + (1 − 2𝛾)𝑧)/(1 − 𝑧), the class 𝑉1,2,1,0 (πœ™)
reduces to the class
𝐡𝛾 = {𝑓 ∈ 𝐴 1 : Re
studied by Chen [5].
󡄨
󡄨󡄨
󡄨󡄨𝑀2 − 𝑑𝑀12 󡄨󡄨󡄨 + (1 + 𝑑) 󡄨󡄨󡄨󡄨𝑀1 󡄨󡄨󡄨󡄨2 ≤ 1,
󡄨
󡄨
󡄨󡄨
󡄨
󡄨󡄨𝑀2 − 𝑑𝑀12 󡄨󡄨󡄨 + (1 − 𝑑) 󡄨󡄨󡄨󡄨𝑀1 󡄨󡄨󡄨󡄨2 ≤ 1,
󡄨
󡄨
𝑓 (𝑧)
> 𝛾} .
𝑧
−1 < 𝑑 ≤ 0,
0 < 𝑑 < 1.
(13)
Lemma 4 (see [6, (7), page 10]). If 𝑀 ∈ Ω and 𝑀(𝑧) = 𝑀1 𝑧 +
𝑀2 𝑧2 + ⋅ ⋅ ⋅ , 𝑧 ∈ 𝐸, then
󡄨
󡄨󡄨
󡄨󡄨𝑀2 − 𝑑𝑀12 󡄨󡄨󡄨 ≤ max {1; |𝑑|} ,
󡄨
󡄨
(14)
for any complex number 𝑑. The result is sharp for the functions
𝑀(𝑧) = 𝑧2 or 𝑀(𝑧) = 𝑧.
Lemma 5 (see [7]). If 𝑀 ∈ Ω, then for any real number π‘ž1 and
π‘ž2 , the following sharp estimate holds:
󡄨
󡄨󡄨
󡄨󡄨𝑀3 + π‘ž1 𝑀1 𝑀2 + π‘ž2 𝑀13 󡄨󡄨󡄨 ≤ 𝐻 (π‘ž1 , π‘ž2 ) ,
󡄨
󡄨
(15)
where
𝐻 (π‘ž1 , π‘ž2 )
0 ≤ 𝛾 < 1, 𝑧 ∈ 𝐸} .
{𝑓 ∈ 𝐴 𝑝 : Re (
(12)
For 𝑑 ≤ −1 or 𝑑 ≥ 1, the equality holds, if and only if 𝑀(𝑧) = 𝑧
or one of its rotation. For −1 ≤ 𝑑 ≤ 1, the equality holds, if
𝑀(𝑧) = 𝑧2 or one of its rotation. the equality holds for 𝑑 = −1,
if and only if 𝑀(𝑧) = 𝑧((πœ† + 𝑧)/(1 + πœ†π‘§)) (0 ≤ πœ† ≤ 1) or one
of its rotation, while for 𝑑 = 1, the equality holds, if and only if
𝑀(𝑧) = −𝑧((πœ† + 𝑧)/(1 + πœ†π‘§)) (0 ≤ πœ† ≤ 1) or one of its rotation.
The above upper bound for −1 < 𝑑 < 1 is sharp, and it can be
improved as follows:
𝛼
σΈ€ 
𝑑 < −1,
−1 ≤ 𝑑 ≤ 1,
𝑑 > 1.
(11)
1,
{
{
{
{
(π‘ž1 , π‘ž2 ) ∈ 𝐷1 ∪ 𝐷2 ,
{
{
{
󡄨󡄨 󡄨󡄨
{
{
π‘ž
󡄨
{
󡄨 2 󡄨󡄨 ,
{
{
7
{
{
{
{ (π‘ž1 , π‘ž2 ) ∈ ⋃ π·π‘˜ ,
{
{
{
π‘˜=3
{
{
1/2
{
σ΅„¨σ΅„¨σ΅„¨π‘ž1 󡄨󡄨󡄨 + 1
{
2
󡄨
󡄨
{
󡄨
󡄨
󡄨
󡄨
{
) ,
(σ΅„¨π‘ž 󡄨 + 1) ( 󡄨󡄨 󡄨󡄨
{
{
{ 3 󡄨 1󡄨
3 (σ΅„¨σ΅„¨π‘ž1 󡄨󡄨 + 1 + π‘ž2 )
={
{
{ (π‘ž1 , π‘ž2 ) ∈ 𝐷8 ∪ 𝐷9 ,
{
1/2
{
{
π‘ž12 − 4
π‘ž12 − 4
{
1
{
{
(
)
(
,
)
π‘ž
{
{
3 2 π‘ž12 − 4π‘ž2
3 (π‘ž2 − 1)
{
{
{
{
{
(π‘ž1 , π‘ž2 ) ∈ 𝐷10 ∪ 𝐷11 \ {±2, 1} ,
{
{
{
1/2
󡄨󡄨 󡄨󡄨
{
{
σ΅„¨σ΅„¨π‘ž1 󡄨󡄨 − 1
2 󡄨󡄨 󡄨󡄨
{
{
) ,
(σ΅„¨π‘ž 󡄨 − 1) ( 󡄨󡄨 󡄨󡄨
{
{
{
3 󡄨 1󡄨
3 (σ΅„¨σ΅„¨π‘ž1 󡄨󡄨 − 1 − π‘ž2 )
{
{
{ (π‘ž1 , π‘ž2 ) ∈ 𝐷12 .
(16)
Journal of Applied Mathematics
3
The extremal function up to the rotations is of the form
𝑀 (𝑧) = 𝑧3 ,
𝑀 (𝑧) = 𝑀0 (𝑧) =
𝑀 (𝑧) = 𝑧,
𝑧 ([(1 − πœ†) πœ€2 + πœ†πœ€1 ] − πœ€1 πœ€2 𝑧)
,
1 − [(1 − πœ†) πœ€1 + πœ†πœ€2 ] 𝑧
𝑀 (𝑧) = 𝑀1 (𝑧) =
𝑧 (𝑑1 − 𝑧)
,
1 − 𝑑1 𝑧
𝑀 (𝑧) = 𝑀2 (𝑧) =
𝑧 (𝑑2 + 𝑧)
,
1 + 𝑑2 𝑧
󡄨󡄨 󡄨󡄨 󡄨󡄨 󡄨󡄨
σ΅„¨σ΅„¨πœ€1 󡄨󡄨 = σ΅„¨σ΅„¨πœ€2 󡄨󡄨 = 1,
πœƒ0
,
2
𝑑0 = (
3 (π‘ž2 − 1) (π‘ž12 − 4π‘ž2 )
𝑑1 = (
𝑏 ± π‘Ž (17)
πœ†=
,
2𝑏
πœƒ0
,
2
2π‘ž2 (π‘ž12 + 2) − 3π‘ž12
1/2
)
,
1/2
󡄨󡄨 󡄨󡄨
σ΅„¨σ΅„¨π‘ž1 󡄨󡄨 + 1
) ,
󡄨󡄨 󡄨󡄨
3 (σ΅„¨σ΅„¨π‘ž1 󡄨󡄨 + 1 + π‘ž2 )
πœƒ0 π‘ž1
=
(
2
2
π‘ž2 (π‘ž12 + 8) − 2 (π‘ž12 + 2)
2π‘ž2 (π‘ž12
+ 2) −
󡄨 󡄨
𝐷9 = { (π‘ž1 , π‘ž2 ) : σ΅„¨σ΅„¨σ΅„¨π‘ž1 󡄨󡄨󡄨 ≥ 2,
3π‘ž12
󡄨 󡄨 󡄨 󡄨
2 σ΅„¨σ΅„¨σ΅„¨π‘ž1 󡄨󡄨󡄨 (σ΅„¨σ΅„¨σ΅„¨π‘ž1 󡄨󡄨󡄨 + 1)
1 2
≤ π‘ž2 ≤
(π‘ž + 8)} ,
󡄨 󡄨
12 1
π‘ž12 + 2 σ΅„¨σ΅„¨σ΅„¨π‘ž1 󡄨󡄨󡄨 + 4
󡄨 󡄨
𝐷11 = { (π‘ž1 , π‘ž2 ) : σ΅„¨σ΅„¨σ΅„¨π‘ž1 󡄨󡄨󡄨 ≥ 4,
󡄨 󡄨 󡄨 󡄨
󡄨 󡄨 󡄨 󡄨
2 σ΅„¨σ΅„¨σ΅„¨π‘ž1 󡄨󡄨󡄨 (σ΅„¨σ΅„¨σ΅„¨π‘ž1 󡄨󡄨󡄨 + 1)
2 σ΅„¨σ΅„¨σ΅„¨π‘ž1 󡄨󡄨󡄨 (σ΅„¨σ΅„¨σ΅„¨π‘ž1 󡄨󡄨󡄨 − 1)
≤
π‘ž
},
≤
󡄨
󡄨
󡄨 󡄨
2
π‘ž12 + 2 σ΅„¨σ΅„¨σ΅„¨π‘ž1 󡄨󡄨󡄨 + 4
π‘ž12 − 2 σ΅„¨σ΅„¨σ΅„¨π‘ž1 󡄨󡄨󡄨 + 4
󡄨 󡄨
𝐷12 = { (π‘ž1 , π‘ž2 ) : σ΅„¨σ΅„¨σ΅„¨π‘ž1 󡄨󡄨󡄨 ≥ 4,
󡄨 󡄨 󡄨 󡄨
2 σ΅„¨σ΅„¨σ΅„¨π‘ž1 󡄨󡄨󡄨 (σ΅„¨σ΅„¨σ΅„¨π‘ž1 󡄨󡄨󡄨 − 1)
2 󡄨 󡄨
≤ π‘ž2 ≤ (σ΅„¨σ΅„¨σ΅„¨π‘ž1 󡄨󡄨󡄨 − 1)} .
󡄨󡄨 󡄨󡄨
2
3
π‘ž1 − 2 σ΅„¨σ΅„¨π‘ž1 󡄨󡄨 + 4
1/2
󡄨󡄨 󡄨󡄨
σ΅„¨σ΅„¨π‘ž1 󡄨󡄨 − 1
𝑑2 = ( 󡄨󡄨 󡄨󡄨
) ,
3 (σ΅„¨σ΅„¨π‘ž1 󡄨󡄨 − 1 − π‘ž2 )
cos
2 󡄨 󡄨
4 󡄨 󡄨
3
󡄨 󡄨
− (σ΅„¨σ΅„¨σ΅„¨π‘ž1 󡄨󡄨󡄨 + 1) ≤ π‘ž2 ≤ (σ΅„¨σ΅„¨σ΅„¨π‘ž1 󡄨󡄨󡄨 + 1) − (σ΅„¨σ΅„¨σ΅„¨π‘ž1 󡄨󡄨󡄨 + 1)} ,
3
27
󡄨 󡄨
𝐷10 = { (π‘ž1 , π‘ž2 ) : 2 ≤ σ΅„¨σ΅„¨σ΅„¨π‘ž1 󡄨󡄨󡄨 ≤ 4,
πœ€1 = 𝑑0 − 𝑒−π‘–πœƒ0 /2 (π‘Ž βˆ“ 𝑏) ,
𝑏 = √ 1 − 𝑑02 sin2
(18)
2. Main Results
).
The sets π·π‘˜ , π‘˜ = 1, 2, . . . , 12 are defined as follows:
Theorem 6. Let πœ™(𝑧) = 1 + 𝐡1 𝑧 + 𝐡2 𝑧2 + 𝐡3 𝑧3 + ⋅ ⋅ ⋅ , where 𝐡𝑛 ,
𝑠 are real with 𝐡1 > 0 and 𝐡2 ≥ 0. Let
2
𝜎1 =
󡄨 󡄨 1 󡄨 󡄨
𝐷1 = {(π‘ž1 , π‘ž2 ) : σ΅„¨σ΅„¨σ΅„¨π‘ž1 󡄨󡄨󡄨 ≤ , σ΅„¨σ΅„¨σ΅„¨π‘ž2 󡄨󡄨󡄨 ≤ 1} ,
2
𝐷2 = {(π‘ž1 , π‘ž2 ) :
1 󡄨󡄨 󡄨󡄨
≤ σ΅„¨π‘ž 󡄨 ≤ 2,
2 󡄨 1󡄨
󡄨 󡄨 󡄨 󡄨
2 σ΅„¨σ΅„¨π‘ž 󡄨󡄨 (σ΅„¨σ΅„¨π‘ž 󡄨󡄨 + 1)
2 󡄨 󡄨
− (σ΅„¨σ΅„¨σ΅„¨π‘ž1 󡄨󡄨󡄨 + 1) ≤ π‘ž2 ≤ 󡄨2 1 󡄨 󡄨󡄨󡄨 1 󡄨󡄨󡄨
},
3
π‘ž1 + 2 σ΅„¨σ΅„¨π‘ž1 󡄨󡄨 + 4
πœ€2 = −𝑒−π‘–πœƒ0 /2 (π‘–π‘Ž ± 𝑏) ,
π‘Ž = 𝑑0 cos
𝐷8 = {(π‘ž1 , π‘ž2 ) :
1 󡄨󡄨 󡄨󡄨
≤ σ΅„¨π‘ž 󡄨 ≤ 2,
2 󡄨 1󡄨
4 󡄨󡄨 󡄨󡄨
3
󡄨 󡄨
(σ΅„¨π‘ž 󡄨 + 1) − (σ΅„¨σ΅„¨σ΅„¨π‘ž1 󡄨󡄨󡄨 + 1) ≤ π‘ž2 ≤ 1} ,
27 󡄨 1 󡄨
× {2 (𝐡2 − 𝐡1 ) − 𝑏𝑝𝐡12
1 2
󡄨 󡄨
𝐷6 = {(π‘ž1 , π‘ž2 ) : 2 ≤ σ΅„¨σ΅„¨σ΅„¨π‘ž1 󡄨󡄨󡄨 ≤ 4, π‘ž2 ≥
(π‘ž + 8)} ,
12 1
2 󡄨 󡄨
󡄨 󡄨
𝐷7 = {(π‘ž1 , π‘ž2 ) : σ΅„¨σ΅„¨σ΅„¨π‘ž1 󡄨󡄨󡄨 ≥ 4, π‘ž2 ≥ (σ΅„¨σ΅„¨σ΅„¨π‘ž1 󡄨󡄨󡄨 − 1)} ,
3
(𝛼 − 1) (𝛼𝑝 + 2𝛽)
2(𝛼𝑝 + 𝛽)
2
},
2
𝜎2 =
(𝛼𝑝 + 𝛽)
𝑏𝑝𝐡12 (𝛼𝑝 + 2𝛽)
× {2 (𝐡2 + 𝐡1 ) − 𝑏𝑝𝐡12
󡄨 󡄨 1 󡄨 󡄨
𝐷3 = {(π‘ž1 , π‘ž2 ) : σ΅„¨σ΅„¨σ΅„¨π‘ž1 󡄨󡄨󡄨 ≤ , σ΅„¨σ΅„¨σ΅„¨π‘ž2 󡄨󡄨󡄨 ≤ −1} ,
2
2 󡄨 󡄨
󡄨 󡄨 1
𝐷4 = {(π‘ž1 , π‘ž2 ) : σ΅„¨σ΅„¨σ΅„¨π‘ž1 󡄨󡄨󡄨 ≥ , π‘ž2 ≤ − (σ΅„¨σ΅„¨σ΅„¨π‘ž1 󡄨󡄨󡄨 + 1)} ,
2
3
󡄨 󡄨
𝐷5 = {(π‘ž1 , π‘ž2 ) : σ΅„¨σ΅„¨σ΅„¨π‘ž1 󡄨󡄨󡄨 ≤ 2, π‘ž2 ≥ 1} ,
(𝛼𝑝 + 𝛽)
𝑏𝑝𝐡12 (𝛼𝑝 + 2𝛽)
(𝛼 − 1) (𝛼𝑝 + 2𝛽)
2(𝛼𝑝 + 𝛽)
2
},
2
𝜎3 =
(𝛼𝑝 + 𝛽)
𝑏𝑝𝐡12 (𝛼𝑝 + 2𝛽)
× {2𝐡2 − 𝑏𝑝𝐡12
Φ (𝑝, 𝛼, 𝛽, πœ‡) =
(𝛼 − 1) (𝛼𝑝 + 2𝛽)
2
2(𝛼𝑝 + 𝛽)
(𝛼𝑝 + 2𝛽) (2πœ‡ + 𝛼 − 1)
2
2(𝛼𝑝 + 𝛽)
},
.
(19)
4
Journal of Applied Mathematics
If 𝑓(𝑧) is of the form (1) and belongs to the class 𝑉𝑝,𝑏,𝛼,𝛽 (πœ™), then
󡄨󡄨
2 󡄨󡄨
σ΅„¨σ΅„¨π‘Žπ‘+2 − πœ‡π‘Žπ‘+1
󡄨󡄨
󡄨
󡄨
𝑏𝑝𝐡12
𝑏𝑝
{
−
(𝐡
Φ (𝑝, 𝛼, 𝛽, πœ‡)) ,
{
2
{
{
2
2 (𝛼𝑝 + 2𝛽)
{
{
{
{
πœ‡ < 𝜎1 ,
{
{
{
{
{
{ 𝑏𝑝𝐡1
,
𝜎1 ≤ πœ‡ ≤ 𝜎2 ,
≤{
{
2 (𝛼𝑝 + 2𝛽)
{
{
{
{
{
𝑏𝑝𝐡12
𝑏𝑝
{
{
{
−
(𝐡
−
Φ (𝑝, 𝛼, 𝛽, πœ‡)) ,
2
{
{
2
{
{ 2 (𝛼𝑝 + 2𝛽)
πœ‡ > 𝜎2 .
{
where 𝐻(π‘ž1 , π‘ž2 ) is defined in Lemma 3 and
π‘ž1 =
2𝐡2 𝑏𝑝𝐡1 (1 − 𝛼) (𝛼𝑝 + 3𝛽)
+
,
𝐡1
2 (𝛼𝑝 + 𝛽) (𝛼𝑝 + 2𝛽)
π‘ž2 =
𝑏𝑝𝐡1 2 (𝛼 − 1) (2𝛼 − 1) (𝛼𝑝 + 3𝛽)
𝐡3
+(
)
3
𝐡1
2
6(𝛼𝑝 + 𝛽)
(20)
+
Proof. Since 𝑓 ∈ 𝑉𝑝,𝑏,𝛼,𝛽 (πœ™), therefore we have for a Schwarz
function
𝑀 (𝑧) = 𝑀1 𝑧 + 𝑀2 𝑧2 + ⋅ ⋅ ⋅ ,
1−
2
𝐡 (𝛼𝑝 + 𝛽)
1
(2 (1 − 2 )
𝑏𝑝𝐡1
𝐡1 (𝛼𝑝 + 2𝛽)
𝑏𝑝𝐡1
󡄨2
󡄨
+
(2πœ‡ + 𝛼 − 1) ) σ΅„¨σ΅„¨σ΅„¨σ΅„¨π‘Žπ‘+1 󡄨󡄨󡄨󡄨
2
(21)
𝑏𝑝𝐡1
,
2 (𝛼𝑝 + 2𝛽)
𝑧𝑓󸀠 (𝑧) 𝑓(𝑧) 𝛼
𝑓(𝑧) 𝛼
2 2
(
) }
+ {(1 − 𝛽) ( 𝑝 ) + 𝛽
𝑏 𝑏
𝑧
𝑝𝑓 (𝑧) 𝑧𝑝
=1+
2
1
(𝛼𝑝 + 𝛽) π‘Žπ‘+1 𝑧 +
(𝛼𝑝 + 2𝛽)
𝑏𝑝
𝑏𝑝
2
} 𝑧2 +
× {2π‘Žπ‘+2 + (𝛼 − 1) π‘Žπ‘+1
𝐡 (𝛼𝑝 + 𝛽)
1
(2 (1 + 2 )
𝑏𝑝𝐡1
𝐡1 (𝛼𝑝 + 2𝛽)
𝑏𝑝𝐡1
󡄨2
󡄨
−
(2πœ‡ + 𝛼 − 1) ) σ΅„¨σ΅„¨σ΅„¨σ΅„¨π‘Žπ‘+1 󡄨󡄨󡄨󡄨
2
+
(22)
(28)
(𝛼 − 1) (𝛼 − 2) 3
π‘Žπ‘+1 } 𝑧3 + ⋅ ⋅ ⋅ .
6
Also, we have
πœ™ (𝑀 (𝑧)) = 1 + 𝐡1 𝑀1 𝑧 + (𝐡1 𝑀2 + 𝐡1 𝑀12 ) 𝑧2
𝑏𝑝𝐡1
.
2 (𝛼𝑝 + 2𝛽)
+ (𝐡1 𝑀3 + 2𝐡2 𝑀1 𝑀2 + 𝐡3 𝑀13 ) 𝑧3 + ⋅ ⋅ ⋅ .
(29)
Comparing the coefficients of 𝑧, 𝑧2 , 𝑧3 and after simple calculations, we obtain
For any complex number πœ‡,
󡄨󡄨
2 󡄨󡄨
σ΅„¨σ΅„¨π‘Žπ‘+2 − πœ‡π‘Žπ‘+1
󡄨󡄨
󡄨
󡄨
󡄨󡄨 𝑏𝑝𝐡
𝑏𝑝𝐡1
𝐡 󡄨󡄨󡄨
󡄨
1
max {1, 󡄨󡄨󡄨
Φ (𝑝, 𝛼, 𝛽, πœ‡) − 2 󡄨󡄨󡄨} .
󡄨󡄨 2
𝐡1 󡄨󡄨
2 (𝛼𝑝 + 2𝛽)
(23)
π‘Žπ‘+1 =
𝑏𝑝𝐡1 𝑀1
,
2 (𝛼𝑝 + 𝛽)
π‘Žπ‘+2 =
𝑏𝑝𝐡1
2 (𝛼𝑝 + 2𝛽)
× {𝑀2 − (
Also,
𝑏𝑝𝐡1
󡄨󡄨
󡄨
σ΅„¨σ΅„¨π‘Žπ‘+3 󡄨󡄨󡄨 ≤
󡄨
󡄨 2 (𝛼𝑝 + 3𝛽) 𝐻 (π‘ž1 , π‘ž2 ) ,
2 (𝛼𝑝 + 3𝛽)
𝑏𝑝
× {π‘Žπ‘+3 + (𝛼 − 1) π‘Žπ‘+1 π‘Žπ‘+2
2
≤
𝑧𝑓󸀠 (𝑧) 𝑓(𝑧) 𝛼
𝑓(𝑧) 𝛼
2 2
) }
+ {(1 − 𝛽) ( 𝑝 ) + 𝛽
(
𝑏 𝑏
𝑧
𝑝𝑓 (𝑧) 𝑧𝑝
(27)
Now,
1−
󡄨󡄨
2 󡄨󡄨
σ΅„¨σ΅„¨π‘Žπ‘+2 − πœ‡π‘Žπ‘+1
󡄨󡄨
󡄨
󡄨
≤
(26)
= πœ™ (𝑀 (𝑧)) .
and for 𝜎3 ≤ πœ‡ ≤ 𝜎2 ,
+
𝑧∈𝐸
such that
󡄨󡄨
2 󡄨󡄨
σ΅„¨σ΅„¨π‘Žπ‘+2 − πœ‡π‘Žπ‘+1
󡄨󡄨
󡄨
󡄨
≤
𝑏𝑝𝐡2 (1 − 𝛼) (𝛼𝑝 + 3𝛽)
.
2 (𝛼𝑝 + 𝛽) (𝛼𝑝 + 2𝛽)
These results are sharp.
Furthermore, for 𝜎1 ≤ πœ‡ ≤ 𝜎3 ,
+
(25)
π‘Žπ‘+3 =
(24)
𝑏𝑝𝐡1 (𝛼 − 1) (𝛼𝑝 + 2𝛽) 𝐡2
− ) 𝑀12 } ,
2
2
𝐡1
2(𝛼𝑝 + 𝛽)
𝑏𝑝𝐡1
{𝑀 + π‘ž1 𝑀1 𝑀2 + π‘ž2 𝑀13 } ,
2 (𝛼𝑝 + 2𝛽) 3
(30)
Journal of Applied Mathematics
5
where π‘ž1 and π‘ž2 are defined in (25). It can be easily followed
from (30) that
2
=
π‘Žπ‘+2 − πœ‡π‘Žπ‘+1
𝑏𝑝𝐡1
{𝑀 − ]𝑀12 } ,
2 (𝛼𝑝 + 2𝛽) 2
(31)
2.1. Application of Theorem 6 to
the Function Defined by Convolutions
where
]=
𝑏𝑝𝐡1
𝐡
Φ (𝑝, 𝛼, 𝛽, πœ‡) − 2 .
2
𝐡1
Corollary 10. For 𝑏 = 2, 𝑝 = 1, 𝛼 = 0, and 𝛽 = 1, the results
from (20) to (22) coincide with the results obtained by Ma and
Minda [2] for the class 𝑆∗ (πœ™).
(32)
The results from (20) to (22) are obtained by using Lemma 3,
(23) by using Lemma 4, and (24) by using Lemma 5. To show
that these results are sharp, we define the functions πΎπœ™π‘› (𝑧),
πΉπœ† (𝑧), and πΊπœ† (𝑧) such that
Theorem 11. Let πœ™(𝑧) = 1 + 𝐡1 𝑧 + 𝐡2 𝑧2 + 𝐡3 𝑧3 + ⋅ ⋅ ⋅ , where
𝐡𝑛 , 𝑠 are real with 𝐡1 > 0 and 𝐡2 ≥ 0. Let
𝜎1 =
σΈ€ 
πΊπœ† (0) =
πΊπœ†σΈ€ 
(33)
− 𝑏𝑝𝐡12
(0) − 1 = 0,
with
σΈ€ 
π‘§πΎπœ™π‘›
(𝑧) πΎπœ™π‘› (𝑧) 𝛼
πΎπœ™π‘› (𝑧) 𝛼
2 2
( 𝑝 ) }
1 − + {(1 − 𝛽) ( 𝑝 ) + 𝛽
𝑏 𝑏
𝑧
π‘πΎπœ™π‘› (𝑧)
𝑧
𝜎2 =
𝑧 (𝑧 + πœ†)
).
1 + πœ†π‘§
𝜎3 =
It is clear that the functions πΎπœ™π‘› , πΉπœ† , πΊπœ† ∈ 𝑉𝑝,𝑏,𝛼,𝛽 (πœ™). Let
πΎπœ™ : = πΎπœ™2 . If πœ‡ < 𝜎1 or πœ‡ > 𝜎2 , then the equality occurs
for the function πΎπœ™ or one of its rotations. For 𝜎1 < πœ‡ < 𝜎2 ,
the equality is attained, if and only if 𝑓 is πΎπœ™3 or one of
its rotations. When πœ‡ = 𝜎1 , then the equality holds for the
function πΉπœ† or one of its rotations. If πœ‡ = 𝜎2 , then the equality
is obtained for the function πΊπœ† or one of its rotations.
Corollary 7. For 𝑏 = 2, the results from (20) to (24) coincide
with the results proved by Ramachandran et al. [8].
Corollary 8. For 𝑏 = 2, 𝑝 = 1, and 𝛽 = 1, the results from
(20) to (22) coincide with the results obtained by Ravichandran
et al. [4] for the class 𝐡𝛼 (πœ™).
Corollary 9. For 𝑏 = 2, 𝛼 = 0, and 𝛽 = 1, the results from
(20) to (24) coincide with the results obtained by Ali et al. [1]
for the class 𝑆𝑝∗ (πœ™).
},
2
(𝛼 − 1) (𝛼𝑝 + 2𝛽)
2
𝑔𝑝+1
Φ∗ (𝑝, 𝛼, 𝛽, πœ‡) =
2(𝛼𝑝 + 𝛽)
2
},
2
(𝛼𝑝 + 𝛽)
𝑔𝑝+2 𝑏𝑝𝐡12 (𝛼𝑝 + 2𝛽)
× {2𝐡2 − 𝑏𝑝𝐡12
(34)
2
(𝛼𝑝 + 𝛽)
𝑔𝑝+2 𝑏𝑝𝐡12 (𝛼𝑝 + 2𝛽)
− 𝑏𝑝𝐡12
𝑧𝐺󸀠 (𝑧) πΊπœ† (𝑧) 𝛼
𝐺 (𝑧) 𝛼
2 2
( 𝑝 ) }
+ {(1 − 𝛽) ( πœ† 𝑝 ) + 𝛽 πœ†
𝑏 𝑏
𝑧
π‘πΊπœ† (𝑧)
𝑧
β‰Ί πœ™ (−
2(𝛼𝑝 + 𝛽)
2
𝑔𝑝+1
𝑧𝐹󸀠 (𝑧) πΉπœ† (𝑧) 𝛼
𝐹 (𝑧) 𝛼
2 2
1 − + {(1 − 𝛽) ( πœ† 𝑝 ) + 𝛽 πœ†
) }
(
𝑏 𝑏
𝑧
π‘πΉπœ† (𝑧) 𝑧𝑝
𝑧 (𝑧 + πœ†)
β‰Ί πœ™(
),
1 + πœ†π‘§
(𝛼 − 1) (𝛼𝑝 + 2𝛽)
× {2 (𝐡2 + 𝐡1 )
β‰Ί πœ™ (𝑧𝑛−1 ) ,
1−
2
(𝛼𝑝 + 𝛽)
𝑔𝑝+2 𝑏𝑝𝐡12 (𝛼𝑝 + 2𝛽)
× {2 (𝐡2 − 𝐡1 )
πΎπœ™π‘› (0) = [πΎπœ™π‘› ] (0) − 1 = 0,
πΉπœ† (0) = πΉπœ†σΈ€  (0) − 1 = 0,
2
𝑔𝑝+1
(𝛼 − 1) (𝛼𝑝 + 2𝛽)
2
2(𝛼𝑝 + 𝛽)
},
(𝛼𝑝 + 2𝛽) (2πœ‡ (𝑔𝑝+2 /𝑔𝑝+1 ) + 𝛼 − 1)
2
2(𝛼𝑝 + 𝛽)
.
(35)
If 𝑓(𝑧) is of the form (1) and belongs to the class 𝑉𝑝,𝑏,𝛼,𝛽,𝑔 (πœ™),
then
󡄨󡄨
2 󡄨󡄨
󡄨󡄨
σ΅„¨σ΅„¨π‘Žπ‘+2 − πœ‡π‘Žπ‘+1
󡄨
󡄨
𝑏𝑝𝐡12 ∗
𝑏𝑝
{
{
−
(𝐡
Φ (𝑝, 𝛼, 𝛽, πœ‡)) ,
{
2
{
2
{
{ 2𝑔𝑝+2 (𝛼𝑝 + 2𝛽)
{
{
{
πœ‡ < 𝜎1 ,
{
{
{
{
𝑏𝑝𝐡1
{
𝜎1 ≤ πœ‡ ≤ 𝜎2 ,
≤ { 2𝑔 (𝛼𝑝 + 2𝛽) ,
{
𝑝+2
{
{
{
{
𝑏𝑝𝐡12 ∗
𝑏𝑝
{
{
{
(
Φ (𝑝, 𝛼, 𝛽, πœ‡) − 𝐡2 ) ,
{
{
2
2𝑔𝑝+2 (𝛼𝑝 + 2𝛽)
{
{
{
πœ‡ > 𝜎2 .
{
(36)
6
Journal of Applied Mathematics
Furthermore, for 𝜎1 ≤ πœ‡ ≤ 𝜎3 ,
Proof. Since 𝑓 ∈ 𝑉𝑝,𝑏,𝛼,𝛽,𝑔 (πœ™), therefore we have for a Schwarz
function 𝑀, such that
󡄨󡄨
2 󡄨󡄨
σ΅„¨σ΅„¨π‘Žπ‘+2 − πœ‡π‘Žπ‘+1
󡄨󡄨
󡄨
󡄨
+
𝛼
2
𝑔𝑝+1
2
𝑏𝑝𝐡1 𝑔𝑝+2
(2 (1 −
+
≤
1−
𝐡2 (𝛼𝑝 + 𝛽)
)
𝐡1 (𝛼𝑝 + 2𝛽)
(𝑓 ∗ 𝑔) (𝑧)
2 2
)
+ { (1 − 𝛽) (
𝑏 𝑏
𝑧𝑝
σΈ€ 
+𝛽
𝑔𝑝+2
𝑏𝑝𝐡1
󡄨2
󡄨
+ 𝛼 − 1) ) σ΅„¨σ΅„¨σ΅„¨σ΅„¨π‘Žπ‘+1 󡄨󡄨󡄨󡄨
(2πœ‡
2
𝑔𝑝+1
𝑏𝑝𝐡1
,
2𝑔𝑝+2 (𝛼𝑝 + 2𝛽)
Now,
𝛼
(37)
1−
(𝑓 ∗ 𝑔) (𝑧)
2 2
)
+ { (1 − 𝛽) (
𝑏 𝑏
𝑧𝑝
and for 𝜎3 ≤ πœ‡ ≤ 𝜎2 ,
σΈ€ 
+𝛽
󡄨󡄨
2 󡄨󡄨
σ΅„¨σ΅„¨π‘Žπ‘+2 − πœ‡π‘Žπ‘+1
󡄨󡄨
󡄨
󡄨
+
2
𝑔𝑝+1
𝑏𝑝𝐡1 𝑔𝑝+2
=1+
2
𝐡 (𝛼𝑝 + 𝛽)
(2 (1 + 2 )
𝐡1 (𝛼𝑝 + 2𝛽)
−
≤
𝛼
𝑧(𝑓 ∗ 𝑔) (𝑧) (𝑓 ∗ 𝑔) (𝑧)
(
) } = πœ™ (𝑀 (𝑧)) .
𝑧𝑝
𝑝 (𝑓 ∗ 𝑔) (𝑧)
(42)
𝑔𝑝+2
𝑏𝑝𝐡1
󡄨2
󡄨
+ 𝛼 − 1) ) σ΅„¨σ΅„¨σ΅„¨σ΅„¨π‘Žπ‘+1 󡄨󡄨󡄨󡄨
(2πœ‡
2
𝑔𝑝+1
𝑏𝑝𝐡1
.
2𝑔𝑝+2 (𝛼𝑝 + 2𝛽)
𝛼
𝑧(𝑓 ∗ 𝑔) (𝑧) (𝑓 ∗ 𝑔) (𝑧)
) }
(
𝑧𝑝
𝑝 (𝑓 ∗ 𝑔) (𝑧)
2
1
(𝛼𝑝 + 𝛽) π‘Žπ‘+1 𝑔𝑝+1 𝑧 +
(𝛼𝑝 + 2𝛽)
𝑏𝑝
𝑏𝑝
2
2
𝑔𝑝+1
} 𝑧2 +
× {2π‘Žπ‘+2 𝑔𝑝+2 + (𝛼 − 1) π‘Žπ‘+1
2
(𝛼𝑝 + 3𝛽)
𝑏𝑝
{π‘Žπ‘+3 𝑔𝑝+3 + (𝛼 − 1) π‘Žπ‘+1 π‘Žπ‘+2 𝑔𝑝+1 𝑔𝑝+2 } 3
×{
(𝛼 − 1) (𝛼 − 2) 3 3
}𝑧 + ⋅⋅⋅ .
+
π‘Žπ‘+1 𝑔𝑝+1
6
}
{
(43)
(38)
Also, we obtain
For any complex number πœ‡,
πœ™ (𝑀 (𝑧)) = 1 + 𝐡1 𝑀1 𝑧 + (𝐡1 𝑀2 + 𝐡1 𝑀12 ) 𝑧2
󡄨󡄨
2 󡄨󡄨
σ΅„¨σ΅„¨π‘Žπ‘+2 − πœ‡π‘Žπ‘+1
󡄨󡄨
󡄨
󡄨
≤
󡄨󡄨 𝑏𝑝𝐡
𝑏𝑝𝐡1
𝐡 󡄨󡄨󡄨
󡄨
1 ∗
max {1, 󡄨󡄨󡄨
Φ (𝑝, 𝛼, 𝛽, πœ‡) − 2 󡄨󡄨󡄨} .
󡄨󡄨 2
𝐡1 󡄨󡄨
2𝑔𝑝+2 (𝛼𝑝 + 2𝛽)
(39)
Also,
𝑏𝑝𝐡1
󡄨󡄨
󡄨
σ΅„¨σ΅„¨π‘Žπ‘+3 󡄨󡄨󡄨 ≤
󡄨
󡄨 2 (𝛼𝑝 + 3𝛽) 𝑔 𝐻 (π‘ž1 , π‘ž2 ) ,
𝑝+3
(40)
+ (𝐡1 𝑀3 + 2𝐡2 𝑀1 𝑀2 + 𝐡3 𝑀13 ) 𝑧3 + ⋅ ⋅ ⋅ .
Comparing the coefficients of 𝑧, 𝑧2 , 𝑧3 and after simple
calculations, we obtain
π‘Žπ‘+1 =
𝑏𝑝𝐡1 𝑀1
,
2𝑔𝑝+1 (𝛼𝑝 + 𝛽)
π‘Žπ‘+2 =
𝑏𝑝𝐡1
2𝑔𝑝+2 (𝛼𝑝 + 2𝛽)
where 𝐻(π‘ž1 , π‘ž2 ) is defined in Lemma 5 and
π‘ž1 =
2𝐡2 𝑏𝑝𝐡1 (1 − 𝛼) (𝛼𝑝 + 3𝛽)
+
,
𝐡1
2 (𝛼𝑝 + 𝛽) (𝛼𝑝 + 2𝛽)
π‘ž2 =
𝑏𝑝𝐡1 2 (𝛼 − 1) (2𝛼 − 1) (𝛼𝑝 + 3𝛽)
𝐡3
+(
)
3
𝐡1
2
6(𝛼𝑝 + 𝛽)
+
𝑏𝑝𝐡2 (1 − 𝛼) (𝛼𝑝 + 3𝛽)
.
2 (𝛼𝑝 + 𝛽) (𝛼𝑝 + 2𝛽)
These results are sharp.
(44)
× {𝑀2 − (
π‘Žπ‘+3 =
𝑏𝑝𝐡1 (𝛼 − 1) (𝛼𝑝 + 2𝛽) 𝐡2
− ) 𝑀12 } ,
2
2
𝐡1
2(𝛼𝑝 + 𝛽)
𝑏𝑝𝐡1
{𝑀 + π‘ž1 𝑀1 𝑀2 + π‘ž2 𝑀13 } .
2𝑔𝑝+3 (𝛼𝑝 + 2𝛽) 3
(45)
(41)
The remaining proof of the theorem is similar to the proof of
Theorem 6.
Corollary 12. For 𝑏 = 2, the results from (36) to (40) coincide
with the results proved by Ramachandran et al. [8] for the class
𝑅𝑝,1,𝛼,𝛽,𝑔 (πœ™).
Journal of Applied Mathematics
7
Corollary 13. For 𝑏 = 2, 𝛼 = 0, and 𝛽 = 1, the results from
(36) to (40) coincide with the results obtained by Ali et al. [1]
∗
(πœ™).
for the class 𝑆𝑝,𝑔
Corollary 14. For 𝑏 = 2, 𝑝 = 1, 𝛼 = 0, and 𝛽 = 1,
𝑔2 =
2
Γ (3) Γ (2 − πœ†)
=
,
Γ (3 − πœ†)
2−πœ†
𝑔3 =
Γ (4) Γ (2 − πœ†)
6
,
=
−
πœ†)
Γ (4 − πœ†)
(2
(3 − πœ†)
𝐡1 =
8
,
πœ‹2
𝐡2 =
(46)
16
,
3πœ‹2
the results from (36) to (38) coincide with the results obtained
by Srivastava and Mishra [9].
Acknowledgment
The work here is fully supported by LRGS/TD/2011/UKM/
ICT/03/02.
References
[1] R. M. Ali, V. Ravichandran, and N. Seenivasagan, “Coefficient
bounds for 𝑝-valent functions,” Applied Mathematics and Computation, vol. 187, no. 1, pp. 35–46, 2007.
[2] W. C. Ma and D. Minda, “A unified treatment of some special
classes of univalent functions,” in Proceedings of the Conference
on Complex Analysis, pp. 157–169, International Press, 1994.
[3] S. Owa, “Properties of certain integral operators,” Southeast
Asian Bulletin of Mathematics, vol. 24, no. 3, pp. 411–419, 2000.
[4] V. Ravichandran, A. Gangadharan, and M. Darus, “FeketeSzegoΜ‹ inequality for certain class of Bazilevic functions,” Far
East Journal of Mathematical Sciences, vol. 15, no. 2, pp. 171–180,
2004.
[5] M. P. Chen, “On the regular functions satisfying 𝑅𝑒{𝑓(𝑧)/𝑧} >
𝜌,” Bulletin of the Institute of Mathematics. Academia Sinica, vol.
3, no. 1, pp. 65–70, 1975.
[6] F. R. Keogh and E. P. Merkes, “A coefficient inequality for certain
classes of analytic functions,” Proceedings of the American
Mathematical Society, vol. 20, pp. 8–12, 1969.
[7] D. V. Prokhorov and J. Szynal, “Inverse coefficients for
(𝛼, 𝛽)-convex functions,” Annales Universitatis Mariae CurieSkΕ‚odowska A, vol. 35, pp. 125–143, 1981.
[8] C. Ramachandran, S. Sivasubramanian, and H. Silverman,
“Certain coefficient bounds for 𝑝-valent functions,” International Journal of Mathematics and Mathematical Sciences, vol.
2007, Article ID 46576, 11 pages, 2007.
[9] H. M. Srivastava and A. K. Mishra, “Applications of fractional
calculus to parabolic starlike and uniformly convex functions,”
Computers & Mathematics with Applications, vol. 39, no. 3-4, pp.
57–69, 2000.
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