Abstract
The present paper deals with the study of a generalized Mittag-Leffler function and associated fractional operator. The operator has been discussed in the space of Lebesgue measurable functions. The composition with Riemann–Liouville fractional integration operator has been obtained.
Keywords: Generalized Mittag-Leffler function, Fractional Calculus
Background
The well-known Mittag-Leffler function named after its originator, the Swedish mathematician Gosta Mittag-Leffler (1846–1927), is defined by (Mittag-Leffler 1903)
| 1 |
The Mittag–Leffler function naturally occurs as the solution of fractional order differential equations. The various generalization of Mittag–Leffler function have been defined and studied by different authors.
Shukla and Prajapati (2007) introduced its generalization , this is defined as
| 2 |
for ; , , and denotes the generalized Pochhammer symbol.
Further, the generalization of (2) is also given by Khan and Ahmed (2013), as follows:
| 3 |
where ; ;; ; ; and
Here, the convergence conditions of (3) have been modified, which was given by Khan and Ahmed (2013).
The following well-known notations and definitions have been used:
Let (Kilbas et al. 2004) be a set of all Lebesgue measurable real or complex valued functions on i.e.
| 4 |
Let , then the Riemann–Liouville left-sided fractional integrals of order (Miller and Ross 1993) is defined as
| 5 |
and the R–L right-sided fractional integral of order is defined as
| 6 |
Miller and Ross (1993) defined the following:
If , ; ; then
| 7 |
and
| 8 |
Khan and Ahmed (2013) proved the following result.
If ; ; and
then for
| 9 |
In continuation of study, in this paper we give the operator associated with as follows:
Let , define
| 10 |
where ; ; ; ; and
Main results
Using the definition (4), one can easily prove following lemma.
Lemma 1
If; ; ; ; and then
| 11 |
Theorem 1
Let. Let; ; andThen
| 12 |
| 13 |
Proof
Using definitions (3) and (5) and further simplification gives
This completes the proof of (12).□
To prove (13), we use definitions (8) and further simplification gives
On applying (12) with replacement of by , the above equation reduces to
From (9), we get
Theorem 2
Let; andandThen
| 14 |
Proof
Taking in (10), we get
Replacing by and simplifying the above equation
and further simplification of above equation gives the proof of Theorem 2.
Theorem 3
Let; andand, Then the operatoris bounded onand
| 15 |
where
| 16 |
Proof
On using the definition (10) and applying Dirichlet’s formula (Samko et al. 1993), we have
Taking in inner integral, this yields
This completes the proof.□
Theorem 4
(Composition with Riemann–Liouville fractional integration operator) Let; ; ; andThen the relation
| 17 |
holds for any summable function
Proof
Applying Dirichlet’s formula (Samko et al. 1993), we get
Substituting in the above equation, we get
Again using (5), this equation becomes
Applying (12), this yields
Using (10), we get
The other equality can also be proved in the similar way.
Theorem 5
Let; ; ; andThen the relation
| 18 |
holds for any continuous function.
Proof
From (8), we have
Again using Theorem 4 and definition (10),
| 19 |
The integrand in the above equation is continuous function on , here we take
| 20 |
Applying same procedures as above, this led the proof of the theorem. This is easy to prove by using mathematical induction method also.
Theorem 6
Let; andThen
| 21 |
Proof
We have
This completes the proof.□
Corollary 1
If; and; Letbe the left-sided operator of Riemann–Liouville fractional integral. Then
| 22 |
Proof is very obvious from Lemma 1 and Theorem 6.
Theorem 7
Let, ; andbe the right-sided operator of Riemann–Liouville fractional integral. Then
Proof
Let
On changing the order of the summation and integration then afterward applying beta function, this gives
Corollary 2
If; and;. Letbe the right-sided operator of Riemann–Liouville fractional integral. Then
| 23 |
Conclusion
In this paper, we proved some properties of generalized Mittag-Leffler functions and also used the fractional calculus approach to prove Theorems 4, 5, 6 and 7.
Authors’ contributions
The authors contributed equally and significantly in writing this article. All authors read and approved the final manuscript.
Competing interests
The authors declare that they have no competing interests.
Contributor Information
Rachana Desai, Email: rachana.132@gmail.com.
I. A. Salehbhai, Email: ibrahimmaths@gmail.com
A. K. Shukla, Email: ajayshukla2@rediffmail.com
References
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