Applications for Certain Classes of Spirallike Functions Defined by the Srivastava-Attiya Operator ()
1. Introduction and Definitions
Let
denote the class of functions
of the form
(1.1)
which are analytic in the open unit disk
. Also let f and g be analytic in
with
. Then we say that f is subordinate to g in
, written
or
, if there exists the Schwarz function w, analytic in
such that
,
and
. We also observe that
if and only if
whenever g is univalent in
.
For functions
, given by
we define the Hadamard product (or convolution) of
and
by
Making use of the principle of subordination between analytic functions, Bhoosnurmath and Devadas [1] considered the subclasses
and
of the class
for
and
as following (see
also [2] and [3] ):
(1.2)
and
(1.3)
We note that
where the classes
and
are introduced and studied by many authors (see [4] [5] and [6] ). Furthermore,
denote the α-spirallike functions studied by Spacek [7] , which are univalent in
.
With a view to define the Srivastava-Attiya transform, we recall here a general Hurwitz-Lerch zeta function, which is defined in [8] by the following series:
For further interesting properties and characteristics of the Hurwitz-Lerch Zeta and other related functions
see [9] [10] and [11] .
Recently, Srivastava and Attiya [12] have introduced the linear operator
, defined in terms of the Hadamard product by
(1.4)
where
(1.5)
The operator
is now popularly known in the literature as the Srivastava-Attiya operator. Various class-mapping properties of the operator
(and its variants) are discussed in the recent works of Srivastava and Attiya [12] , Liu [13] , Murugusundaramoorthy [14] , Yuan and Liu [15] and others.
It is easy to observe from (1.1) and (1.4) that
(1.6)
We note that:
1)
;
2)
(see Alexander [16] );
3)
(see Flett [17] );
4)
(see Jung et al. [18] );
5)
(see Sǎlǎgean [19] ).
It is easily verified from (1.6) that
(1.7)
Next, by using the linear operator
, we introduce the following new
classes of analytic functions for
,
,
and
:
(1.8)
and
(1.9)
It follows from the definitions (1.8) and (1.9) that
(1.10)
In this article, we investigate some convolution properties and coefficient estimates for the classes
and
. Furthermore, several inclusion properties and relevant connections of the results presented here with those obtained in earlier works are also discussed.
2. Convolution Properties and Coefficient Estimates
Unless otherwise mentioned, we will assume in the reminder of this paper that
,
and
. In order to establish our convolution
properties, we shall need the following lemmas due to Bhoosnurnath and Devadas [1] [2] .
Lemma 2.1 ( [1] ). The function
defined by (1.1) is in the class
if and only if
(2.1)
where
(2.2)
Lemma 2.2 ( [2] Lemma 3 with n = 1). The function
defined by (1.1) is in the class
if and only if
(2.3)
where
(2.4)
We begin by proving the following theorem.
Theorem 2.3 The function
defined by (1.1) is in the class
if and only if
Proof. From Lemma 2.1, we find that
if and only if
(2.5)
where M is given by (2.2). Then, by applying (1.6), the left hand side of (2.5) becomes
which completes the proof of Theorem 2.3.
Theorem 2.4 The function
defined by (1.1) is in the class
if and only if
Proof. From Lemma 2.2, we observe that
if and only if
(2.6)
where N is given by (2.4). Then, by using (1.6), the left hand side of (2.6) may be written as
which evidently proves Theorem 2.4.
Next, we determine coefficients estimates for a function of the form (1.1) to be in the classes
and
.
Theorem 2.5 Let
and
. The function
defined by (1.1) is in the class
if its coefficients satisfy the condition
Proof. Since
and
by virtue of Theorem 2.3, we conclude that
. Thus, the proof of Theorem 2.5 is completed.
By using arguments similar to those above with Theorem 2.4, we can prove the following theorem.
Theorem 2.6 Let
and
. The function
defined by (1.1) is in the class
if its coefficients satisfy the condition
3. Inclusion Properties and Applications
To prove the inclusion properties for the classes
and
, we shall require the following lemma due to Eenigenburg et al. [20] .
Lemma 3.1 ( [20] ). Let
be convex univalent in
with
for all
. If
is analytic in
with
, then
implies that
.
By applying Lemma 3.1, we prove
Theorem 3.2 Let
and
. If
(3.1)
then
Proof. Let
for
and
, and set
(3.2)
where
is analytic in
with
. By applying the identity (1.7), we obtain
(3.3)
Making use of the logarithmic differentiation on both side in (3.3), we have
(3.4)
Since the function
is convex univalent in
with
, from (3.1) we see that
Thus, by using Lemma 3.1 and (3.4), we observe that
in
, so that
. This completes the proof of theorem 3.2.
Theorem 3.3 Let
and
. Suppose that (3.1) holds for all
. Then
Proof. Applying (1.10) and Theorem 3.2, we observe that
which evidently proves Theorem 3.3.
Putting
and
in Theorem 3.2 and 3.3, we have the following corollary.
Corollary 3.4 Suppose that
and
(3.5)
Then
and
Finally, we consider the generalized Bernardi-Libera-Livingston integral operator
defined by (cf. [21] [22] and [23] )
(3.6)
Theorem 3.5 Let
,
and
. Suppose that
(3.7)
If
, then
.
Proof. If we set
(3.8)
where
is analytic in
with
. By virtue of (3.5), we observe that
(3.9)
In view of (3.7) and (3.8), we have
By using same argument as in the proof of Theorem 3.2 with (3.6), we conclude that
. This evidently completes the proof of Theorem 3.5.
Theorem 3.6 Let
,
and
. Suppose that (3.6) holds for all
. If
, then
.
Proof. By using Theorem 3.4, it follows that
which completes the proof of Theorem 3.6.
Acknowledgements
This work was supported by Daegu National University of Education Research grant in 2017.