Integral Means and fractional calculus operators for comprehensive family of

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General Mathematics Vol. 14, No. 3 (2006), 61–78
Integral Means and fractional calculus
operators for comprehensive family of
univalent functions with negative
coefficients 1
B. A. Frasin, G. Murugusundaramoorthy and N.
Mageshand
Abstract
In this paper, we obtain the integral means inequality for the function f (z) belongs to the class U T (Φ, Ψ, γ, k) of analytic and univalent
functions with negative coefficients defined in [3] with the extremal
functions of this class. And also we derive some distortion theorems
using fractional calculus techniques for the class U T (Φ, Ψ, γ, k).
2000 Mathematics Subject Classification: 30C45.
Keywords:Univalent, starlike, convex, uniformly convex, uniformly
starlike, Hadamard product, integral means, Fractional calculus
1
Received 28 August, 2006
Accepted for publication (in revised form) 19 September, 2006
61
62
B. A. Frasin, G.Murugusundaramoorthy and N.Mageshand
1
Introduction and definitions
Let A denote the class of functions of the form
∞
X
(1.1)
f (z) = z +
an z n
n=2
which are analytic and univalent in the open disc U = {z : z ∈ C, |z| < 1}.
Also denote by T the subclass of A consisting of functions of the form
(1.2)
f (z) = z −
∞
X
an z n , an ≥ 0, z ∈ U
n=2
introduced and studied by Silverman [16].
Following Gooodman [5, 6], Rønning [12, 13] introduced and studied the
following subclasses
(i) A function f ∈ A is said to be in the class Sp (γ, k), k−uniformly starlike
functions of order γ, if it satisfies the condition
¯ ′
¯
½ ′
¾
¯ zf (z)
¯
zf (z)
(1.3)
Re
− γ > k ¯¯
− 1¯¯ , z ∈ U,
f (z)
f (z)
0 ≤ γ < 1 and k ≥ 0.
(ii) A function f ∈ A is said to be in the class U CV (γ, k), k−uniformly
convex functions of order γ, if it satisfies the condition
¯ ′′ ¯
½
¾
¯ zf (z) ¯
zf ′′ (z)
¯ , z ∈ U,
(1.4)
Re 1 + ′
− γ > k ¯¯ ′
f (z)
f (z) ¯
0 ≤ γ < 1 and k ≥ 0.
Indeed it follows from (1.3) and (1.4) that
(1.5)
f ∈ U CV (γ, k) ⇔ zf ′ ∈ Sp (γ, k).
Definition 1.1 ([3]). Given γ(−1 ≤ γ < 1), k(k ≥ 0) and functions
Φ(z) = z +
∞
X
n=2
n
λn z and Ψ(z) = z +
∞
X
n=2
µn z n
Integral Means and fractional calculus operators...
63
analytic in U, such that λn ≥ 0, µn ≥ 0 and λn ≥ µn for n ≥ 2, we let f ∈ A
is in U (Φ, Ψ, α, β) if (f ∗ Ψ)(z) 6= 0 and
¯
¯
¾
½
¯ (f ∗ Φ)(z)
¯
(f ∗ Φ)(z)
¯
−γ ≥ k¯
− 1¯¯ , ∀ z ∈ U.
Re
(f ∗ Ψ)(z)
(f ∗ Ψ)(z)
where (*) stands for the Hadamard product.
Further let U T (Φ, Ψ, α, β) = U (Φ, Ψ, α, β) ∩ T.
We note that, by taking suitable choice of Φ, Ψ, α and β we obtain the
following subclasses studied in literature.
1. U T
³
z
z
, 1−z
,
(1−z)2
´
γ, 1 = T Sp (γ) (Subrmanian et al., [22])
2. U T
³
z
z
, 1−z
,
(1−z)2
´
γ, k = Sp T (γ, k) (Bharati et al., [1])
3. U T
³
z+z 2
z
, (1−z)
2,
(1−z)3
´
0, 1 = U CT (Subrmanian et al., [21])
4. U T
³
z+z 2
z
, (1−z)
2,
(1−z)3
´
0, k = U CT (k) (Subrmanian et al., [21])
5. U T
³
z+z 2
z
, (1−z)
2,
(1−z)3
´
γ, 1 = U CT (γ) (Bharati et al., [1])
6. U T
³
z
z+z 2
, (1−z)
2,
(1−z)3
´
γ, k = U CT (γ, k) (Bharati et al., [1])
7. U T
³
z
z
, 1−z
,
(1−z)2
´
γ, 0 = ST∗ (γ) (Silverman [16])
64
B. A. Frasin, G.Murugusundaramoorthy and N.Mageshand
8. U T
³
z
z+z 2
, (1−z)
2,
(1−z)3
´
γ, 0 = KT (γ) (Silverman [16])
9. U T (Φ, Ψ, γ, 0) = ET (Φ, Ψ, γ) (Juneja et al.[7]).
10. U T (Φ, Ψ, 1+β−2α
, 0) = BT (Φ, Ψ, α, β) (Frasin [4]).
2(1−α)
In fact many subclasses of T are defined and studied to investigate coefficient estimates, extreme points, convolution properties and closure properties etc. suitably choosing Φ, Ψ, γ and k.
In this paper, we obtain integral means inequalities for functions f (z) ∈
U T (Φ, Ψ, γ, k) and also we state integral means results for the classes studied in [21, 1, 22, 16, 4] as corollaries.
For analytic functions g(z) and h(z) with g(0) = h(0), g(z) is said to be
subordinate to h(z) if there exists an analytic function w(z) so that w(0) =
0, |w(z)| < 1 (z ∈ U) and g(z) = h(w(z)), we denote this subordination by
g(z) ≺ h(z).
To prove our main results, we need the following lemmas.
Lemma 1.1 ([3]). A function f (z) ∈ U T (Φ, Ψ, γ, k) for γ(−1 ≤ γ < 1)
and k(k ≥ 0) if and only if
(1.1)
∞
X
[(1 + k)λn − (γ + k)µn ]an ≤ 1 − γ.
n=2
The result is sharp with the extremal functions
(1.2)
fn (z) = z −
1−γ n
z , n≥2
σ(γ, k, n)
Integral Means and fractional calculus operators...
65
where σ(γ, k, n) = (1 + k)λn − (γ + k)µn , γ(−1 ≤ γ < 1), k(k ≥ 0) and
n ≥ 2.
Lemma 1.2 ([8]). If the functions f (z) and g(z) are analytic in U with
g(z) ≺ f (z) then
(1.3)
Z2π
0
2
¯
¯
¯g(reiθ )¯ ηdθ ≤
Z2π
0
¯
¯
¯f (reiθ )¯ ηdθ η > 0, z = reiθ and 0 < r < 1.
Integral mean
Applying Lemma 1.1 and Lemma 1.2, we prove the following theorem.
Theorem 2.1. Let η > 0. If f (z) ∈ U T (Φ, Ψ, γ, k), −1 ≤ γ < 1, k ≥ 0 and
iθ
{σ(γ, k, n)}∞
n=2 is non-decreasing sequence, then for z = re and 0 < r < 1,
we have
Z2π
(2.1)
0
where f2 (z) = z −
¯
¯
¯f (reiθ )¯ ηdθ ≤
Z2π
0
¯
¯
¯f2 (reiθ )¯ ηdθ
1−γ
z2.
σ(γ,k,2)
(1−γ) 2
Proof. Let f (z) of the form (1.2) and f2 (z) = z − σ(γ,k,2)
z , then we must
show that
¯
¯
Z2π ¯
Z2π ¯¯
∞
¯
X
¯
¯
(1
−
γ)
¯
n−1 ¯
an z ¯ ηdθ ≤ ¯¯1 −
z ¯¯ ηdθ.
¯1 −
¯
¯
σ(γ, k, 2)
n=2
0
0
By Lemma 1.2, it suffices to show that
1−
∞
X
n=2
an z n−1 ≺ 1 −
1−γ
z
σ(γ, k, 2)
66
B. A. Frasin, G.Murugusundaramoorthy and N.Mageshand
Setting
(2.2)
1−
∞
X
an z n−1 = 1 −
n=2
1−γ
w(z).
σ(γ, k, 2)
From (2.2) and (1.1), we obtain
¯
¯∞
¯
¯X σ(γ, k, 2)
¯
¯
an z n−1 ¯
|w(z)| = ¯
¯
¯ n=2 1 − γ
≤ |z|
∞
X
σ(γ, k, n)
1−γ
n=2
an
≤ |z| < 1.
This completes the proof of the Theorem 2.1.
By taking different choices of Φ, Ψ, γ and k in the above theorem, we
can state the following integral means results for various subclasses studied
earlier [21, 1, 22, 16, 4].
Corollary 2.2. Let η > 0. If f (z) ∈ U T
then for z = reiθ ; 0 < r < 1, we have
Z2π
(2.3)
0
where g2 (z) = z −
z2
6
¯
¯
¯f (reiθ )¯ ηdθ ≤
Z2π
0
³
z+z 2
z
, (1−z)
2,
(1−z)3
¯
¯
¯g2 (reiθ )¯ ηdθ
.
Corollary 2.3. Let η > 0. If f (z) ∈ U T
³
z
z+z 2
, (1−z)
2,
(1−z)3
and k ≥ 0, then for z = reiθ ; 0 < r < 1, we have
(2.4)
Z2π
0
where g2 (z) = z −
´
0, 1 = U CT,
¯
¯
¯f (reiθ )¯ ηdθ ≤
z2
2(k+2)
.
Z2π
0
¯
¯
¯g2 (reiθ )¯ ηdθ
´
0, k = U CT (k)
Integral Means and fractional calculus operators...
Corollary 2.4. Let η > 0. If f (z) ∈ U T
³
67
z
z+z 2
, (1−z)
2,
(1−z)3
and −1 ≤ γ < 1, then for z = reiθ ; 0 < r < 1, we have
(2.5)
Z2π
0
where g2 (z) = z −
¯
¯
¯f (reiθ )¯ ηdθ ≤
(1−γ) 2
z
2(3−γ)
Z2π
0
´
γ, 1 = U CT (γ)
¯
¯
¯g2 (reiθ )¯ ηdθ
.
Corollary 2.5. Let η > 0. If f (z) ∈ U T
³
z+z 2
z
, (1−z)
2,
(1−z)3
´
γ, k = U CT (γ, k),
−1 ≤ γ < 1 and k ≥ 0, then for z = reiθ ; 0 < r < 1, we have
(2.6)
Z2π
0
where g2 (z) = z −
¯
¯
¯f (reiθ )¯ ηdθ ≤
(1−γ)
z2
2(2−γ+k)
Z2π
0
¯
¯
¯g2 (reiθ )¯ ηdθ
.
Corollary 2.6. Let η > 0. If f (z) ∈ U T
³
z
z
, 1−z
,
(1−z)2
−1 ≤ γ < 1, then for z = reiθ ; 0 < r < 1, we have
(2.7)
Z2π
0
where g2 (z) = z −
¯
¯
¯f (reiθ )¯ ηdθ ≤
(1−γ) 2
z
(3−γ)
Z2π
0
´
γ, 1 = T Sp (γ) and
¯
¯
¯g2 (reiθ )¯ ηdθ
.
Corollary 2.7. Let η > 0. If f (z) ∈ U T
³
z
z
, 1−z
,
(1−z)2
´
γ, k = Sp T (γ, k),
−1 ≤ γ < 1 and k ≥ 0, then for z = reiθ ; 0 < r < 1, we have
(2.8)
Z2π
0
where g2 (z) = z −
By taking γ =
¯
¯
¯f (reiθ )¯ ηdθ ≤
(1−γ)
z2 .
(2−γ+k)
1+β−2α
and
2(1−α)
result of Frasin and Darus [4].
Z2π
0
¯
¯
¯g2 (reiθ )¯ ηdθ
k = 0 in Theorem 2.1 we get the following
68
B. A. Frasin, G.Murugusundaramoorthy and N.Mageshand
, 0) = BT (Φ, Ψ, α, β),
Corollary 2.8. Let η > 0. If f (z) ∈ U T (Φ, Ψ, 1+β−2α
2(1−α)
0 ≤ β < 1 and 0 ≤ α < 1, then for z = reiθ ; 0 < r < 1, we have
Z2π
(2.9)
0
¯
¯
¯f (reiθ )¯ ηdθ ≤
Z2π
0
¯
¯
¯g2 (reiθ )¯ ηdθ
(1−β) 2
z and ψ(α, β, 2) = 2(1 − α)λ2 − (1 + β − 2α)µ2 .
where g2 (z) = z − ψ(α,β,2)
³
´
z
z
Corollary 2.9.Let η > 0. If f (z) ∈ U T (1−z)2 , 1−z , γ, 0 = ST∗ (γ) and
γ ≥ 0, then for z = reiθ ; 0 < r < 1, we have
(2.10)
Z2π
0
where g2 (z) = z −
¯
¯
¯f (reiθ )¯ ηdθ ≤
1−γ 2
z
2−γ
Z2π
0
¯
¯
¯g2 (reiθ )¯ ηdθ
.
Corollary 2.10.Let η > 0. If f (z) ∈ U T
³
z
z+z 2
, (1−z)
2,
(1−z)3
and γ ≥ 0, then for z = reiθ ; 0 < r < 1, we have
(2.11)
Z2π
0
where g2 (z) = z −
Remark 2.11.
¯
¯
¯f (reiθ )¯ ηdθ ≤
1−γ
z2
2(2−γ)
Z2π
0
´
γ, 0 = KT (γ),
¯
¯
¯g2 (reiθ )¯ ηdθ
.
If we take γ = 0 in ST∗ (γ) of Corollary 2.9 and KT (γ)
of Corollary 2.10, we get the integral means results obtained by Silverman
[17].
3
Fractional Calculus
Many essentially equivalent definitions of fractional calculus (that is fractional derivatives and fractional integrals) have been given in the literature
(cf., e.g., [2],[9],[11], [14], [15], [18]and[19]). We find it to be convenient to
Integral Means and fractional calculus operators...
69
recall here the following definitions which are used earlier by Owa [10](and,
subsequently, by Srivastava and Owa [19]).
Definition 3.1. The fractional integral of order ξ is defined, for a function
f (z), by
Dz−ξ f (z)
(3.1)
1
=
Γ(ξ)
z
Z
0
f (ζ)
dζ
(z − ζ)1−ξ
(ξ > 0),
where the function f (z) is analytic in a simply-connected region of the zplane containing the origin and the multiplicity of the the function (z −
ζ)ξ−1 is removed by requiring the function log(z−ζ) to be real when z−ζ > 0.
Definition 3.2. The fractional derivative of order ξ is defined, for a function f (z), by
(3.2)
d
1
Dz ξf (z) =
Γ(−ξ) dz
Z
0
z
f (ζ)
dζ
(z − ζ)1−ξ
(0 ≤ ξ < 1),
where the function f (z) is constrained, and the multiplicity of the the function (z − ζ)−ξ is removed as in Definition 3.1
Definition 3.3. Under the hypotheses of Definition 3.2, the fractional
derivative of order n + λ is defined by
(3.3)
Dzm+ξ f (z) =
dm
D ξf (z)
dz m z
(0 ≤ ξ < 1; m ∈ N0 ).
Remark 3.4. From Definition 3.2, we have Dz0 f (z) = f (z), which in
view of Definition 3.3 yields Dzm+0 f (z) =
dm
D0 f (z)
dz m z
= f (m) (z). Thus,
limDz−ξ f (z) = f (z) and limDz1−ξ f (z) = f ′ (z) .
ξ→0
ξ→0
We need the following definition of fractional integral operator given by
Srivastava, Saigo and Owa[20].
70
B. A. Frasin, G.Murugusundaramoorthy and N.Mageshand
Definition 3.5 For real number η > 0, µ and δ, the fractional integral
η,µ,δ
operator I0,z
is defined by
(3.4)
η,µ,δ
I0,z
f (z)
z −η−µ
=
Γ(η)
Z
z
(z − t)η−1 F (η + µ, −δ; η; 1 − t/z)f (t)dt,
0
where a function f (z) is analytic in a simply-connected region of the z-plane
containing the origin with the order
f (z) = O(|z| ε)
(z → 0),
with ε > max{0, µ − δ} − 1. Here F (a, b; c; z) is the Gauss hypergeometric
function defined by
(3.5)
F (a, b; c; z) =
∞
X
(a)n (b)n
n=0
(c)n (1)n
zn,
where (ν)n is the Pochhammer symbol defined by
(3.6)

Γ(ν + n)  1
(ν)n =
=
 ν(ν + 1)(ν + 2) · · · (ν + n − 1)
Γ(ν)
(n = 0)
(n ∈ N)
and the multiplicity of (z − t)η−1 is removed by requiring log (z − t) to be
real when z − t > 0.
Remark 3.4. For µ = −η, we note that
η,−η,δ
I0,z
f (z) = Dz−η f (z).
In order to prove our result for the fractional integral operator, we have
to recall here the following lemma due to Srivastava, Saigo and Owa [20].
Integral Means and fractional calculus operators...
71
Lemma 3.7. If η > 0 and n > µ − δ − 1, then
(3.7)
η,µ,δ n
I0,z
z =
Γ(n + 1)Γ(n − µ + δ + 1) n−µ
z .
Γ(n − µ + 1)Γ(n + η + δ + 1)
With aid of Lemma 3.7, we prove
Theorem 3.8. Let η > 0, µ < 2, η + δ > −2, µ − δ < 2, µ(η + δ) ≤ 3η.
Let the function f (z) defined by (1.2) be in the class U T (Φ, Ψ, γ, k). If
{σ(γ, k, n)}∞
n=2 is a non-decreasing sequence. Then we have
(3.8)
µ
¶
¯
¯
Γ(2 − µ + δ) |z|1−µ
2(1 − γ)(2 − µ + δ)
¯
¯ η,µ,δ
1−
|z|
¯I0,z f (z)¯ ≥
Γ(2 − µ)Γ(2 + η + δ)
(2 − µ)(2 + η + δ)σ(γ, k, 2)
and
(3.9)
¶
µ
¯
¯
Γ(2 − µ + δ) |z|1−µ
2(1 − γ)(2 − µ + δ)
¯ η,µ,δ
¯
|z|
1+
¯I0,z f (z)¯ ≤
Γ(2 − µ)Γ(2 + η + δ)
(2 − µ)(2 + η + δ)σ(γ, k, 2)
for z ∈ U0 , where
(3.10)

 U
U0 =
 U−{0}
(µ ≤ 1),
(µ > 1).
The equalities in (3.8) and(3.9) are attained for the function f (z) given by
(3.11)
f (z) = z −
2(1 − γ)(2 − µ + δ)
z2.
(2 − µ)(2 + η + δ)σ(γ, k, 2)
Proof. By using Lemma 3.7, we have
72
B. A. Frasin, G.Murugusundaramoorthy and N.Mageshand
η,µ,δ
I0,z
f (z) =
(3.12)
Γ(2 − µ + δ)
z 1−µ
Γ(2 − µ)Γ(2 + η + δ)
−
∞
X
n=2
Γ(n + 1)Γ(n − µ + δ + 1)
an z n−µ
Γ(n − µ + 1)Γ(n + η + δ + 1)
(z ∈ U0 ).
Letting
G(z) =
(3.13)
Γ(2 − µ)Γ(2 + η + δ)
η,µ,δ
zµI0,z
f (z)
Γ(2 − µ + δ)
=z−
∞
X
g(n)an z n ,
n=2
where
(3.14)
g(n) =
(2 − µ + δ)n−1 (1)n
(2 − µ)n−1 (2 + η + δ)n−1
(n ≥ 2),
we can see that the function g(k) is non-increasing for integers n(n ≥ 2),and
thus we have
(3.15)
0 < g(n) ≤ g(2) =
2(2 − µ + δ)
.
(2 − µ)(2 + η + δ)
From Lemma 1.1, we obtain
(3.16)
σ(γ, k, 2)
∞
X
n=2
an ≤
∞
X
n=2
σ(γ, k, n)an ≤ 1 − γ
Integral Means and fractional calculus operators...
73
Hence, using (3.15) and (3.16), we have
(3.17)
|G(z)| ≥ |z| − g(2) |z|
2
∞
X
an ≥ |z| −
2(1 − γ)(2 − µ + δ)
|z|2 ,
(2 − µ)(2 + η + δ)σ(γ, k, 2)
∞
X
an ≤ |z| +
2(1 − γ)(2 − µ + δ)
|z|2 ,
(2 − µ)(2 + η + δ)σ(γ, k, 2)
n=2
and
(3.18)
|G(z)| ≤ |z| + g(2) |z|
2
n=2
for z ∈ U0 , where U0 is defined by (3.10). This completes the proof Theorem
3.8.
By using the same proof as in Theorem 3.8, we can prove
Theorem 3.9. Let the function f (z) be defined by (1.2) be in the class
U T (Φ, Ψ, γ, k) . If {σ(γ, k, n)/n}∞
n=2 is a non-decreasing sequence. Then
we have
(3.19)
¶
µ
¯
¯
Γ(2 − µ + δ) |z|1−µ
4(1 − γ)(2 − µ + δ)
¯
¯ η,µ,δ
|z|
1−
¯I0,z f (z)¯ ≥
Γ(2 − µ)Γ(2 + η + δ)
(2 − µ)(2 + η + δ)σ(γ, k, 2)
and
(3.20)
µ
¶
¯
¯
Γ(2 − µ + δ) |z|1−µ
4(1 − γ)(2 − µ + δ)
¯
¯ η,µ,δ
1+
|z|
¯I0,z f (z)¯ ≤
Γ(2 − µ)Γ(2 + η + δ)
(2 − µ)(2 + η + δ)σ(γ, k, 2)
for z ∈ U0 , where U0 is defined by (3.10). The equalities in (3.19) and (3.20)
are attained for the function f (z) given by (3.11).
Taking µ = −η = −ξ Theorem 3.8, we get
74
B. A. Frasin, G.Murugusundaramoorthy and N.Mageshand
Corollary 3.10. Let the function f (z) defined by (1.2) be in the class
U T (Φ, Ψ, γ, k). If {σ(γ, k, n)}∞
n=2 is a non-decreasing sequence. Then we
have
(3.21)
and
(3.22)
1+ξ
¯
¯ −ξ
¯Dz f (z)¯ ≥ |z|
Γ(2 + ξ)
µ
1+ξ
¯
¯ −ξ
¯Dz f (z)¯ ≤ |z|
Γ(2 + ξ)
µ
1+
¶
2(1 − γ)
|z|
1−
(2 + ξ)σ(γ, k, 2)
2(1 − γ)
|z|
(2 + ξ)σ(γ, k, 2)
¶
for ξ > 0, z ∈ U. The result is sharp for the function
(3.23)
Dz−ξ f (z)
|z|1+ξ
=
Γ(2 + ξ)
µ
¶
2(1 − γ)
|z| .
1−
(2 + ξ)σ(γ, k, 2)
Taking µ = −η = ξ in Theorem 3.9, we get
Corollary 3.11.Let the function
f (z) defined by (1.2) be in the class
U T (Φ, Ψ, γ, k). If {σ(γ, k, n)/n}∞
n=2 is a non-decreasing sequence. Then
we have
(3.24)
|z|1−ξ
|Dz ξf (z)| ≥
Γ(2 − ξ)
µ
|z|1−ξ
|Dz ξf (z)| ≤
Γ(2 − ξ)
µ
4(1 − γ)
|z|
1−
(2 − ξ)σ(γ, k, 2)
¶
and
(3.25)
¶
4(1 − γ)
|z|
1+
(2 − ξ)σ(γ, k, 2)
for 0 ≤ ξ < 1, z ∈ U. The result is sharp for the function given by (3.23).
Integral Means and fractional calculus operators...
75
Letting ξ = 0 in Corollary 3.10, we have
Corollary 3.12 ([3]). Let the function f (z) defined by (1.2) be in the
class U T (Φ, Ψ, γ, k). If {σ(γ, k, n)}∞
n=2 is a non-decreasing sequence. Then
we have
1−γ
1−γ
|z| ≤ |f (z)| ≤ 1 +
|z|
σ(γ, k, 2)
σ(γ, k, 2)
for ξ > 0, z ∈ U. The result is sharp for the function
(3.26)
1−
1−γ 2
z .
σ(γ, k, 2)
Letting ξ → 1 in Corollary 3.11,we have
(3.27)
f (z) = z −
Corollary 2.7 ([3]).Let the function f (z) defined by (1.2) be in the class
U T (Φ, Ψ, γ, k). If {σ(γ, k, n)/n}∞
n=2 is a non-decreasing sequence. Then we
have
2(1 − γ)
2(1 − γ)
|z| ≤ |f ′ (z)| ≤ 1 +
|z|
σ(γ, k, 2)
σ(γ, k, 2)
for 0 ≤ ξ < 1, z ∈ U. The result is sharp for the function given by (3.27).
(3.28)
1−
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Department of Mathematics,
Al al-Bayt University,
P.O. Box: 130095 Mafraq, Jordan.
E-mail address: bafrasin@yahoo.com.
School of Science and Humanities,
Vellore Institute of Technology, Deemed University,
Vellore - 632014, India.
E-mail address:gmsmoorthy@yahoo.com
Department of Mathematics,
Adhiyamaan College of Engineering,
Hosur - 635109,India.
E-mail address: nmagi 2000@yahoo.co.in
starlike
func-
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