- Research
- Open access
- Published:
Note on fractional Mellin transform and applications
SpringerPlus volume 5, Article number: 100 (2016)
Abstract
In this article, we define the fractional Mellin transform by using Riemann–Liouville fractional integral operator and Caputo fractional derivative of order \(\alpha \ge 0\) and study some of their properties. Further, some properties are extended to fractional way for Mellin transform.
Background
Mellin transform occurs in many areas of engineering and applied mathematics. According to Flajolet et al. (1995), Hjalmar Mellin (1854–1933) gave his name to the Mellin transform that associates to a function f(x) defined over the positive reals, the complex function \({\mathcal{M}}[f(x);s]\). It is closely related to the Laplace and Fourier transforms. We start by recalling the definition and some important properties of the Mellin transform. The domain of definition is an open strip, \(\langle a, b \rangle ,\) of complex numbers \(s = \sigma + it\) such that \(0 \le a < \sigma < b\). Here we recollect the definition from Flajolet et al. (1995) and some properties which are mentioned in Kiliçman (2006).
Definition 1
(Flajolet et al. 1995) Let f(x) be locally Lebesgue integrable over \((0, \infty )\). The Mellin transform of f(x) is defined by
The largest open strip \(\langle a, b \rangle\) in which the integral converges is called the fundamental strip. The inverse Mellin transform is defined as the following:
Theorem 1
Let f(x) be integrable with fundamental strip \(\langle \alpha ,\beta \rangle\). If c is such that \(\alpha <c<\beta\) and \(f^{*}(s=c + it) ={\mathcal{M}}[f(x);s]\) is integrable, then the equality
holds almost everywhere. Moreover, if f(x) is continuous, then equality holds everywhere on \(( 0, +\infty).\)
Theorem 2
(Kiliçman 2004) Let f be Mellin transformable function defined on \({\mathbb{R}}_{+}\). If differentiation under the integral sign is allowed, then we have
- (1):
-
\({\mathcal{M}}[f^{(n)}(x);s]= \int _{0}^{\infty }f^{n}(x)x^{s-1}dx=\dfrac{(-1)^{n}\Gamma (s)}{\Gamma (s-n)}M[f(x);s-n]\)
- (2):
-
\({\mathcal{M}}[x^{n}f^{(n)}(x);s]=\int _{0}^{\infty }x^{n}f^{n}(x)x^{s-1}dx=(-s)^{n}M[f(x);s]\)
- (3):
-
\(\left( \dfrac{d}{ds}\right) ^{n} {\mathcal{M}}[f(x);s]=\int _{0}^{\infty }f(x)(\log x)^{n}x^{s-1}dx=M[(\log x)^{n}f(x);s-1]\)
- (4):
-
\({\mathcal{M}}\left[ \int _{0}^{x}f(t)dt;s\right] =\int _{0}^{\infty }\left( \int _{0}^{x}f(t)dt\right) x^{s-1}dx=-\frac{1}{s}M[f(x);s+1].\)
For more information readers may refer to Butzer and Jansche (1997), Erdélyi et al. (1954), Flajolet et al. (1985), Podlubny (1999) and Butzer and Jansche (1998), and (Kiliçman 2006).
Basic definitions of fractional calculus
Fractional calculus is a generalization of the classical calculation and it has been used successfully in various fields of science and engineering. In fact, there are new opportunities in mathematics and theoretical physics appear, when order differential operator or operator becomes an integral arbitrary parameter. The fractional calculus is a powerful tool for the physical description systems that have long-term memory and long term spatial interactions see Podlubny (1999), Miller and Ross (1993), Hilfer (2000), Kilbas et al. (2006) and Samko et al. (1993).
There are different types of fractional derivatives in the current literature. One of the new fractional derivatives that was recently proposed is called Caputo–Fabrizio derivative see Atangana (2016), Caputo and Fabrizio (2015) and Losada and Nieto (2015). However in our study, Riemann–Liouville and Caputo derivatives have been used.
The use of integral transforms to deal with fractional derivatives traces back to Riemann and Liouville (Oldham and Spanier 1974; Widder 1971). Further, in Dattoli et al. (2003) the authors have shown that combined use of integral transforms and special polynomials provides a powerful tool to deal with fractional derivatives and integrals.
In this section, we give the definitions of Riemann–Liouville and Caputo fractional operators along the main properties as follows:
Definition 2
A real function f(x), \(x>0\) is said to be in space \(C_{\mu } , \mu \in {\mathbb{R}}\) if there exists a real number \(p>\mu\), such that \(f(x)=x^{p}f_{1}(x)\) where \(f(x)\in C(0,\infty )\), and it is said to be in the space \(C_{\mu } ^{n}\) if \(f^{n}\in C_{\mu } ,n\in {\mathbb{N}}.\)
Definition 3
The Riemann–Liouville fractional derivative operator of order \(\alpha\) of a function f(x) is defined as:
Definition 4
(Podlubny 1999) The Riemann–Liouville fractional integral operator of order \(\alpha \ge 0\) of a function \(f\in C_{\mu }, \mu \ge -1\) is defined as:
in particular \(J^{0}f(x)=f(x).\)
Some properties of Riemann–Liouville fractional operator
If \(\alpha , \beta\) are two positive real number, then:
-
(1)
\(D^{\alpha }(D^{-\beta }f(x))=D^{\alpha -\beta }f(x),\)
-
(2)
\(J^{\alpha }J^{\beta }f(x)=J^{\alpha +\beta }f(x),\)
-
(3)
\(J^{\alpha }J^{\beta }f(x)=J^{\beta }J^{\alpha }f(x).\)
Definition 5
(Caputo 1969) The Caputo fractional derivative of \(f\in C_{-1}^{m} , m\in {\mathbb{N}},\) is defined as
for \(m-1<\alpha \le m\), \(m\in {\mathbb{N}}.\)
Theorem 3
If \(m-1 <\alpha \le m , m\in N , f\in C_{\mu }^{m}, \mu >-1,\) then the following two properties hold
- (1):
-
\(D_{c}^{\alpha }\left[ J_{c}^{\alpha }f(x)\right] =f(x),\)
- (2):
-
\(J^{\alpha }\left[ D_{c}^{\alpha }f(x)\right] =f(x)-\sum\nolimits _{k=0}^{m-1}f^{k}(0)\left( \dfrac{x^{k}}{k!}\right).\)
Definition 6
(Fractional Cauchy’s integral formula) (Jumarie 2010) Assume that \(f: U\rightarrow {\mathbb{C}}\), \(z \rightarrow f(z)\) is a fractional analytic function of order \(\alpha = \frac{1}{{N}}, {N} \ge 1\), N integer. For every \(a\in U\) consider the disk \(D \subset U\) with the boundary defined by the circle \(\gamma\) of which the radius is r. Then f (z) is actually infinitely \(\alpha\)th differentiable, with
As a special case when \(n=1,\) the fractional derivative can be written in the form:
Main results
In this part, some properties of Mellin transform of fractional operator have shown.
Theorem 4
Let f(x) be Mellin transformable function on \((0,\infty ),\) where \(0\le n-1< \alpha <n,\) then
- (1):
-
\({\mathcal{M}}[D_{c}^{\alpha } J_{c}^{\alpha } f(x) ;s]={\mathcal{M}}[ f(x) ;s]\),
- (2):
-
\({\mathcal{M}}[J^{\alpha }D_{c}^{\alpha } f(x) ;s]={\mathcal{M}}[ f(x);s ]-\sum\nolimits_{k=0}^{m-1} \dfrac{f^{k}(0)}{k!(k+s)}\), \(\ Re(s)>-Re(k)\),
- (3):
-
\({\mathcal{M}}[J^{\alpha }J^{\beta }f(x);s]=\dfrac{\Gamma (1-\alpha -\beta -s)}{\Gamma (1-s)} M[f(t);\alpha +\beta +s]\).
Proof
-
(1)
The result is obtained by applying Mellin transform to both sides of the first property (1) in Theorem 3
$${\mathcal{M}}\left[ D_{c}^{\alpha }J_{c}^{\alpha }f(x);s\right] ={\mathcal{M}}[f(x);s].$$
-
(2)
We apply Mellin transform on the part (2) in Theorem 3, then we obtain
$$\begin{aligned} {\mathcal{M}}\left[ J^{\alpha }D_{c}^{\alpha }f(x);s\right]&= {} {\mathcal{M}}[f(x);s]-{\mathcal{M}}\left[ \sum\limits_{k=0}^{m-1}\dfrac{f^{k}(0)x^{k}}{k!};s\right] \\&= {} {\mathcal{M}}[f(x);s]-\sum\limits_{k=0}^{m-1}\dfrac{f^{k}(0)}{k!}\int _{0}^{\infty }x^{k+s-1}dx \\&= {} {\mathcal{M}}[f(x);s]-\sum\limits_{k=0}^{m-1}\dfrac{f^{k}(0)}{k!(k+s)},\quad Re(s)> -Re(k) \end{aligned}$$
-
(3)
Now,we are applying Mellin transform of \(J^{\alpha } J^{\beta }\)
$$\begin{aligned} {\mathcal{M}}\left[ J^{\alpha } J^{\beta } f(x);s\right] ={\mathcal{M}}\left[ J^{\alpha +\beta } f(x);s\right]&= {} \int _{0}^{\infty }x^{s-1}\frac{1}{\Gamma (\alpha +\beta )}\int _{0}^{x} (x-t)^{\alpha +\beta -1}f(t)dtdx \\&= {} \dfrac{1}{\Gamma (\alpha +\beta )}\int _{0}^{\infty }f(t)dt\int _{t}^{\infty }x^{s-1}(x-t)^{\alpha +\beta -1}dx. \end{aligned}$$Setting \(x=\frac{t}{u}\), then the x-integral becomes
$$t^{\alpha +\beta +s-1}\int _{0}^{1}u^{-\alpha -\beta -s}(1-u)^{\alpha +\beta -1}du.$$So,
$$\begin{aligned} {\mathcal{M}}\left[ J^{\alpha } J^{\beta } f(x);s\right]&= {} \dfrac{1}{\Gamma (\alpha +\beta )}\int _{0}^{\infty }t^{\alpha +\beta +s-1}f(t)dt\int _{0}^{1}u^{-\alpha -\beta -s}(1-u)^{\alpha +\beta -1}du,\\&\quad \hbox{where}\quad Re(\alpha +\beta )> 0,\quad Re(\alpha +\beta +s)<1. \end{aligned}$$After using beta function which is defined by \(B(\alpha ,\beta )=\int _{0}^{1}t^{\alpha -1}(1-t)^{\beta -1}dt\) and the fact that \(B(\alpha ,\beta )=\dfrac{\Gamma (\alpha )\Gamma (\beta )}{\Gamma (\alpha +\beta )},\) hence obtain,
$$\begin{aligned} {\mathcal{M}}\left[ J^{\alpha } J^{\beta } f(x);s\right]&= {} \frac{\Gamma (1-\alpha -\beta -s)}{\Gamma (1-s)}\int _{0}^{\infty }t^{\alpha +\beta +s-1}f(t)dt\\&= {} \frac{\Gamma (1-\alpha -\beta -s)}{\Gamma (1-s)} {\mathcal{M}}[f(t);\alpha +\beta +s]. \end{aligned}$$
Theorem 5
Let f be Mellin transformable defined on \({\mathbb{R}}_{{+}}\), then
-
(1)
\({\mathcal{M}}\left[ f^{\frac{1}{2}}(x);s\right] =\int _{0}^{\infty }x^{s-1}f^{\frac{1}{2}}(x)dx ,\) by using fractional integration by parts and fractional derivative of power function, we obtain
$$\begin{aligned} {\mathcal{M}}\left[ f^{\frac{1}{2}}(x);s\right]&= {} \int _{0}^{\infty }x^{s-1}f^{\frac{1}{2}}(x)dx =\int _{0}^{\infty }f(x)D^{\frac{1}{2}}x^{s-1}dx \\&= {} \dfrac{\Gamma (s)}{\Gamma (s-\frac{1}{2})}{\mathcal{M}}\left[ f(x);s-\frac{1}{2}\right] \end{aligned}$$
-
(2)
\({\mathcal{M}}\left[ f^{\frac{3}{2}}(x);s\right] =\int _{0}^{\infty }x^{s-1}f^{\frac{3}{2}}(x)dx,\) by using fractional integration by parts and fractional derivative of power function, we obtain
$$\begin{aligned} {\mathcal{M}}\left[ f^{\frac{3}{2}}(x);s\right]&= {} \int _{0}^{\infty }x^{s-1}f^{\frac{3}{2}}(x)dx =\int _{0}^{\infty }f(x)D^{\frac{3}{2}}x^{s-1}dx \\&= {} \dfrac{\Gamma (s)}{\Gamma (s-\frac{3}{2})}{\mathcal{M}}\left[ f(x);s-\frac{3}{2}\right]. \end{aligned}$$
Continuing by the induction, then the results in Theorem 5 can be extended to further fractional derivatives as the following theorem:
Theorem 6
Let f be Mellin transformable function on \({\mathbb{R}}_{+}\), and f is a fractional derivative function for all \(n-1<\alpha <n,\ n\in {\mathbb{N}}\), then:
Remark 4
By using the same technique in above theorem, Mellin transform of fractional integral can be yielded as the following formula:
Theorem 7
Let f be Mellin transformable defined on \({\mathbb{R}}_{{+}}\), then
By the same way as in Theorem 5, the next result follows:
Example 1
Solve the problem:
By applying the Mellin transform to both side and on using the Theorem 7 we have
By solving the equation and applying the inverse Mellin transform by using complex inversion integral in order to cover the f(x) explicitly as the solution
Theorem 8
Let \(f\in X_{(a,b)}\) and holomorphic on the strip St(a, b). In addition f is Mellin transformable function, then
where \(s\in St(a,b),\) and \(0\le \alpha \le 1\).
Proof
We set \(\varphi (x)= s+\delta e^{ix}\), where St(a, b) contains the circle \({C}_{\delta }(s)\) of radius \(\delta\) with s.
First of all, for \(u > 0,\) let us consider
Secondly, we apply fractional Cauchy’s integral formula when \(n=1\) for fractional derivatives
By another application of fractional Cauchy’s integral formula, we obtain
Therefore, the proof of Theorem 8 is fulfilled. \(\square\)
Example 2
Let \(f(x)=e^{-x}\) we apply Theorem 8 then we have
So,
Example 3
Let f(x) be Delta function, \(f(x) = \delta (x-a)\), \(a>0\) and by Theorem 8, then we get
Thus, \({\mathcal{M}}\left[ (\log x)^{\alpha }\delta (x-a);s\right] =a^{s-1}(\log a)^{\alpha }.\)
Remark 5
For special cases we have the following:
-
(1)
If \(\alpha =1\) then the formula (3) turns to [part (3) in Theorem 2] when \(n=1,\)
-
(2)
In the Example 2,
-
(i)
if \(\alpha =0\) then \({\mathcal{M}}[e^{-x};s]= \Gamma (s),\)
-
(ii)
if \(\alpha =1\) then we get the result
-
$${\mathcal{M}}\left[ (\log x)e^{-x};s\right] =\left( \frac{d}{ds}\right) \Gamma (s)\quad \hbox{where}\quad Re (s)>0 ,\quad \hbox{see Oberhettinger (1974)},$$
-
-
(i)
-
(3)
In the Example 3,
Theorem 9
Let \({\mathcal{M}}[f(x);s]\) be Mellin transform of the function f(x) in \((0,\infty ),\) where \(0<3\alpha <1\), then
- (1):
-
\({\mathcal{M}}\left[ D^{3\alpha } f(x);s\right] = \dfrac{\Gamma (s)}{\Gamma (s)-3\alpha }{\mathcal{M}}[f(x);s-3\alpha ]\),
- (2):
-
\({\mathcal{M}}\left[ D^{\alpha }D^{\alpha }D^{\alpha }f(x);s\right] =\dfrac{(\Gamma (s))^{3}}{(\Gamma (s-\alpha ))^{3}}{\mathcal{M}}[f(x);s-3\alpha ]\).
Proof
-
(1)
The result is given directly from Theorem 6 then we obtain
$${\mathcal{M}}\left[ D^{3\alpha }f(x);s\right] =\dfrac{\Gamma (s)}{\Gamma (s)-3\alpha }{\mathcal{M}}\left[ f(x);s-3\alpha \right] ,\quad {\rm {where}} \quad 0 <3\alpha <1.$$
-
(2)
Also we apply the formula in Theorem 6 part by part as the following:
$$\begin{aligned} {\mathcal{M}}\left[ D^{\alpha }D^{\alpha }D^{\alpha }f(x);s\right]&= {} \dfrac{\Gamma (s)}{\Gamma (s-\alpha )}{\mathcal{M}}\left[ D^{\alpha }D^{\alpha }f(x);s-\alpha \right] \\&= {} \dfrac{\Gamma (s)}{\Gamma (s-\alpha )}\dfrac{\Gamma (s)}{\Gamma (s-\alpha )}{\mathcal{M}}\left[ D^{\alpha }f(x);s-2\alpha \right] \\&= {} \dfrac{\Gamma (s)}{\Gamma (s-\alpha )}\dfrac{\Gamma (s)}{\Gamma (s-\alpha )}\dfrac{\Gamma (s)}{\Gamma (s-\alpha )}{\mathcal{M}}\left[ f(x);s-3\alpha \right] \\&= {} \dfrac{(\Gamma (s))^{3}}{(\Gamma (s-\alpha ))^{3}}{\mathcal{M}}[f(x);s-3\alpha ]. \end{aligned}$$From (1) and (2) we observe that
$${\mathcal{M}}\left[ D^{\alpha }D^{\alpha }D^{\alpha }f(x);s\right] \ne {\mathcal{M}}\left[ D^{3\alpha } f(x);s\right].$$
Conclusion
In this paper, some properties of fractional calculus are proposed by applying Mellin integral transform, and some applications are also given. Further, the results in fractional sense by using Mellin transform are in agreement with ordinary way in the existing literature. In fact, Mellin integral transform and its inverse are powerful to solve some kinds of fractional equations with variable coefficients, that will be a future study.
References
Atangana A (2016) On the new fractional derivative and application to nonlinear Fisher’s reaction–diffusion equation. Appl Math Comput 273:948–956
Butzer PL, Jansche S (1997) A direct approach to the Mellin transform. J Fourier Anal Appl 3(4):325–376
Butzer PL, Jansche S (1998) Mellin transform theory and the role of its differential and integral operators. In: Rusev P, Dimovski I, Kiryakova V (eds) Proceedings of the 2nd international workshop in transform methods and special functions (Varna 96). Bulg. Acad. Sci., Sofia, pp 63–83
Caputo M (1969) Elasticita e dissipazione. Zani-Chelli, Bologna
Caputo M, Fabrizio M (2015) A new definition of fractional derivative without singular Kernel. Prog Fract Differ Appl 1(2):73–85
Dattoli G, Ricci PE, Cesarano C, Vazquez L (2003) Special polynomials and fractional calculus. Math Comput Model 37:729–733
Erdélyi A, Magnus W, Oberhettinger F, Tricomi FG (1954) Tables of integral transforms, vol 1. McGraw-Hill, New York City
Flajolet P, Regnier M, Sedgewick R (1985) Some uses of the Mellin integral transform in the analysis of algorithms. In: Apostolico A, Galil Z (eds) Combinatorial algorithms on words. Springer, Berlin
Flajolet P, Gourdon X, Dumas P (1995) Mellin transforms and asymptotics: harmonic sums. Theor. Comput Sci 144(1–2):3–58
Graf U (2010) Introduction to hyperfunctions and their integral transforms: an applied and computational approach. Birkhauser, Basel
Hilfer R (2000) Applications of fractional calculus in physics. World Scientific, Hackensack
Jumarie G (2010) Cauchy’s integral formula via modified Riemann–Liouville derivative for analytic functions of fractional order. Appl Math Lett 23(12):1444–1450
Kilbas AA, Srivastava HM, Trujillo JJ (2006) Theory and applications of fractional differential equations. North-Holland mathematical studies, vol 204. Elsevier, Amsterdam
Kiliçman A (2004) A note on Mellin transform and distributions. Math Comput Appl 9(1):65–72
Kiliçman A (2006) Distributions theory and neutrix calculus. University Putra Malaysia Press (Penerbit UPM), Serdang, Malaysia
Losada J, Nieto JJ (2015) Properties of a new fractional derivative without singular Kernel. Prog Fract Differ Appl 1(2):87–92
Miller KS, Ross B (1993) An introduction to the fractional calculus and fractional differential equations. Wiley, New York
Oberhettinger F (1974) Tables of Mellin transforms. Springer, New York
Oldham H, Spanier N (1974) The fractional calculus. Academic Press, San Diego
Podlubny I (1999) Fractional differential equations. Academic Press, San Diego
Samko SG, Kilbas AA, Marichev OI (1993) Fractional integrals and derivatives: theory and applcations. Gordon and Breach, New York [translated from the Russian edition, Minsk (1987)]
Widder DV (1971) An introduction to transform theory. Academic Press, New York
Authors’ contributions
Both the authors jointly worked on deriving the results. Both authors read and approved the final manuscript .
Acknowledgements
The authors would like to thank the referees for valuable suggestions and comments, which helped the authors to improve this article substantially.
Competing interests
The authors declare that they have no competing interests.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
About this article
Cite this article
Kılıçman, A., Omran, M. Note on fractional Mellin transform and applications. SpringerPlus 5, 100 (2016). https://doi.org/10.1186/s40064-016-1711-x
Received:
Accepted:
Published:
DOI: https://doi.org/10.1186/s40064-016-1711-x