### - Art Gallery -

In mathematics, Katugampola fractional operators are integral operators that generalize the Riemann–Liouville and the Hadamard fractional operators into a unique form. The Katugampola fractional integral generalizes both the Riemann–Liouville fractional integral and the Hadamard fractional integral into a single form and It is also closely related to the Erdelyi–Kober  operator that generalizes the Riemann–Liouville fractional integral. Katugampola fractional derivative has been defined using the Katugampola fractional integral  and as with any other fractional differential operator, it also extends the possibility of taking real number powers or complex number powers of the integral and differential operators.

Definitions

These operators have been defined on the following extended-Lebesgue space.

Let $${\textit {X}}_{c}^{p}(a,b),\;c\in \mathbb {R} ,\,1\leq p\leq \infty }$$ be the space of those Lebesgue measurable functions f on $$[a,b]}$$ for which $$\|f\|_{{\textit {X}}_{c}^{p}}<\infty }$$, where the norm is defined by 

{\begin{aligned}\|f\|_{{\textit {X}}_{c}^{p}}={\Big (}\int _{a}^{b}|t^{c}f(t)|^{p}{\frac {dt}{t}}{\Big )}^{1/p}<\infty ,\end{aligned}}}

for $$1\leq p<\infty ,\,c\in \mathbb {R} }$$ and for the case $$p=\infty }$$

{\begin{aligned}\|f\|_{{\textit {X}}_{c}^{\infty }}={\text{ess sup}}_{a\leq t\leq b}[t^{c}|f(t)|],\quad (c\in \mathbb {R} ).\end{aligned}}}

Katugampola fractional integral

It is defined via the following integrals 

$$({}^{\rho }{\mathcal {I}}_{a+}^{\alpha }f)(x)={\frac {\rho ^{1-\alpha }}{\Gamma (\alpha )}}\int _{a}^{x}{\frac {\tau ^{\rho -1}f(\tau )}{(x^{\rho }-\tau ^{\rho })^{1-\alpha }}}\,d\tau ,}$$ (1)

for $$x>a}$$ and $$\operatorname {Re} (\alpha )>0.}$$ This integral is called the left-sided fractional integral. Similarly, the right-sided fractional integral is defined by,

$$({}^{\rho }{\mathcal {I}}_{b-}^{\alpha }f)(x)={\frac {\rho ^{1-\alpha }}{\Gamma ({\alpha })}}\int _{x}^{b}{\frac {\tau ^{\rho -1}f(\tau )}{(\tau ^{\rho }-x^{\rho })^{1-\alpha }}}\,d\tau .}$$ (2)

for $$\textstyle x<b}$$ and $$\textstyle \operatorname {Re} (\alpha )>0}.$$

These are the fractional generalizations of the n {\displaystyle n} n-fold left- and right-integrals of the form

$$\int _{a}^{x}t_{1}^{\rho -1}\,dt_{1}\int _{a}^{t_{1}}t_{2}^{\rho -1}\,dt_{2}\cdots \int _{a}^{t_{n-1}}t_{n}^{\rho -1}f(t_{n})\,dt_{n}}$$

and

$$\int _{x}^{b}t_{1}^{\rho -1}\,dt_{1}\int _{t_{1}}^{b}t_{2}^{\rho -1}\,dt_{2}\cdots \int _{t_{n-1}}^{b}t_{n}^{\rho -1}f(t_{n})\,dt_{n}}$$ for $$\textstyle n\in \mathbb {N} ,}$$

respectively. Even though the integral operators in question are close resemblance of the famous Erdélyi–Kober operator, it is not possible to obtain the Hadamard fractional integrals as a direct consequence of the Erdélyi–Kober operators. Also, there is a corresponding fractional derivative, which generalizes the Riemann–Liouville and the Hadamard fractional derivatives. As with the case of fractional integrals, the same is not true for the Erdélyi–Kober operator.
Katugampola fractional derivative

As with the case of other fractional derivatives, it is defined via the Katugampola fractional integral.

Let $$\alpha \in \mathbb {C} ,\ \operatorname {Re} (\alpha )\geq 0,n=[\operatorname {Re} (\alpha )]+1}$$ and $$\rho >0.}$$ The generalized fractional derivatives, corresponding to the generalized fractional integrals (1) and (2) are defined, respectively, for $$0\leq a<x<b\leq \infty }$$, by
The half-derivative of the function $$f(x)=x^{0.5}}$$ for the Katugampola fractional derivative.
The half derivative of the function $$f(x)=x^{\nu }}$$ for the Katugampola fractional derivative for $$\alpha =0.5$$ and $$\rho =2}.$$

{\begin{aligned}{\big (}{}^{\rho }{\mathcal {D}}_{a+}^{\alpha }f{\big )}(x)&={\bigg (}x^{1-\rho }\,{\frac {d}{dx}}{\bigg )}^{n}\,\,{\big (}{}^{\rho }{\mathcal {I}}_{a+}^{n-\alpha }f{\big )}(x)\\&={\frac {\rho ^{\alpha -n+1}}{\Gamma ({n-\alpha })}}\,{\bigg (}x^{1-\rho }\,{\frac {d}{dx}}{\bigg )}^{n}\int _{a}^{x}{\frac {\tau ^{\rho -1}f(\tau )}{(x^{\rho }-\tau ^{\rho })^{\alpha -n+1}}}\,d\tau ,\end{aligned}}}

and

{\begin{aligned}{\big (}{}^{\rho }{\mathcal {D}}_{b-}^{\alpha }f{\big )}(x)&={\bigg (}-x^{1-\rho }\,{\frac {d}{dx}}{\bigg )}^{n}\,\,{\big (}{}^{\rho }{\mathcal {I}}_{b-}^{n-\alpha }f{\big )}(x)\\&={\frac {\rho ^{\alpha -n+1}}{\Gamma ({n-\alpha })}}{\bigg (}-x^{1-\rho }{\frac {d}{dx}}{\bigg )}^{n}\int _{x}^{b}{\frac {\tau ^{\rho -1}f(\tau )}{(\tau ^{\rho }-x^{\rho })^{\alpha -n+1}}}\,d\tau ,\end{aligned}}}

respectively, if the integrals exist.

These operators generalize the Riemann–Liouville and Hadamard fractional derivatives into a single form, while the Erdelyi–Kober fractional is a generalization of the Riemann–Liouville fractional derivative. When, $$b=\infty }$$ , the fractional derivatives are referred to as Weyl-type derivatives.
Caputo–Katugampola fractional derivative

There is a Caputo-type modification of the Katugampola derivative that is now known as the Caputo–Katugampola fractional derivative. Let $$f\in L^{1}[a,b],\alpha \in (0,1]}$$ and $$\rho$$. The C-K fractional derivative of order $$\alpha$$of the function $$f:[a,b]\rightarrow \mathbb {R} ,}$$ with respect to parameter $$\rho$$ can be expressed as

$${}^{C}{\mathcal {D}}_{a+}^{\alpha ,\rho }f(t)={\frac {\rho ^{\alpha }t^{1-\alpha }}{\Gamma (1-\alpha )}}{\frac {d}{dt}}\int _{a}^{t}{\frac {s^{\rho -1}}{(t^{\rho }-s^{\rho })^{\alpha }}}{\big [}f(s)-f(a){\big ]}\,ds.}$$

It satisfies the following result. Assume that $$f\in C^{1}[a,b]}$$, then the C-K derivative has the following equivalent form

$${}^{C}{\mathcal {D}}_{a+}^{\alpha ,\rho }f(t)={\frac {\rho ^{\alpha }}{\Gamma (1-\alpha )}}\int _{a}^{t}{\frac {f^{\prime }(s)}{(t^{\rho }-s^{\rho })^{\alpha }}}ds.}$$

Hilfer–Katugampola fractional derivative

Another recent generalization is the Hilfer-Katugampola fractional derivative. Let order $$0<\alpha<1$$ and type $$0\leq {\beta }\leq {1}}$$. The fractional derivative (left-sided/right-sided), with respect to x, with $$\rho >0$$, is defined by

{\begin{aligned}({^{\rho }{\mathcal {D}}_{a\pm }^{\alpha ,\beta }}\varphi )(x)&=\left(\pm \,{^{\rho }{\mathcal {J}}_{a\pm }^{\beta (1-\alpha )}}\left(t^{\rho -1}{\frac {d}{dt}}\right){^{\rho }{\mathcal {J}}_{a\pm }^{(1-\beta )(1-\alpha )}}\varphi \right)(x)\\&=\left(\pm \,{^{\rho }{\mathcal {J}}_{a\pm }^{\beta (1-\alpha )}}\delta _{\rho }\,{^{\rho }{\mathcal {J}}_{a\pm }^{(1-\beta )(1-\alpha )}}\varphi \right)(x),\end{aligned}}}

where $$\delta _{\rho }=t^{\rho -1}{\frac {d}{dt}}},$$ for functions $$\varphi$$in which the expression on the right hand side exists, where $${\mathcal {J}}$$ is the generalized fractional integral given in (1).
Mellin transform

As in the case of Laplace transforms, Mellin transforms will be used specially when solving differential equations. The Mellin transforms of the left-sided and right-sided versions of Katugampola Integral operators are given by 
Theorem

Let $$\alpha \in {\mathcal {C}},\ \operatorname {Re} (\alpha )>0,}$$ and $$\rho >0.}$$ Then,

{\begin{aligned}&{\mathcal {M}}{\bigg (}{}^{\rho }{\mathcal {I}}_{a+}^{\alpha }f{\bigg )}(s)={\frac {\Gamma {\big (}1-{\frac {s}{\rho }}-\alpha {\big )}}{\Gamma {\big (}1-{\frac {s}{\rho }}{\big )}\,\rho ^{\alpha }}}\,{\mathcal {M}}f(s+\alpha \rho ),\quad \operatorname {Re} (s/\rho +\alpha )<1,\,x>a,\\&{\mathcal {M}}{\bigg (}{}^{\rho }{\mathcal {I}}_{b-}^{\alpha }f{\bigg )}(s)={\frac {\Gamma {\big (}{\frac {s}{\rho }}{\big )}}{\Gamma {\big (}{\frac {s}{\rho }}+\alpha {\big )}\,\rho ^{\alpha }}}\,{\mathcal {M}}f(s+\alpha \rho ),\quad \operatorname {Re} (s/\rho )>0,\,x<b,\\\end{aligned}}}

for $$f\in {\textit {X}}_{s+\alpha \rho }^{1}(\mathbb {R^{+}} )}$$, if $${\mathcal {M}}f(s+\alpha \rho )}$$ exists for $$s\in \mathbb {C} }.$$

Katugampola operators satisfy the following Hermite-Hadamard type inequalities:
Theorem

Let α > 0 {\displaystyle \alpha >0} \alpha >0 and ρ > 0. {\displaystyle \rho >0.} {\displaystyle \rho >0.}. If f {\displaystyle f} f is a convex function on [ a , b ] {\displaystyle [a,b]} {\displaystyle [a,b]}, then

$$f\left({\frac {a+b}{2}}\right)\leq {\frac {\rho ^{\alpha }\Gamma (\alpha +1)}{4(b^{\alpha }-a^{\alpha })^{\alpha }}}\left[{}^{\rho }{\mathcal {I}}_{a+}^{\alpha }F(b)+{}^{\rho }{\mathcal {I}}_{b-}^{\alpha }F(a)\right]\leq {\frac {f(a)+f(b)}{2}},}$$

where $$F(x)=f(x)+f(a+b-x),\;x\in [a,b].}.$$

When $$\rho \rightarrow 0^{+}}$$, in the above result, the following Hadamard type inequality holds:
Corollary

Let $$\alpha >0$$. If f is a convex function on $$[a,b]}$$, then

$$f\left({\frac {a+b}{2}}\right)\leq {\frac {\Gamma (\alpha +1)}{4\left(\ln {\frac {b}{a}}\right)^{\alpha }}}\left[\mathbf {I} _{a+}^{\alpha }F(b)+\mathbf {I} _{b-}^{\alpha }F(a)\right]\leq {\frac {f(a)+f(b)}{2}},}$$

where $$\mathbf {I} _{a+}^{\alpha }}$$ and $$\mathbf {I} _{b-}^{\alpha }}$$ are left- and right-sided Hadamard fractional integrals.
Recent Development

These operators have been mentioned in the following works:

Fractional Calculus. An Introduction for Physicists, by Richard Herrmann 
Fractional Calculus of Variations in Terms of a Generalized Fractional Integral with Applications to Physics, Tatiana Odzijewicz, Agnieszka B. Malinowska and Delfim F. M. Torres, Abstract and Applied Analysis, Vol 2012 (2012), Article ID 871912, 24 pages 
Introduction to the Fractional Calculus of Variations, Agnieszka B Malinowska and Delfim F. M. Torres, Imperial College Press, 2015
Advanced Methods in the Fractional Calculus of Variations, Malinowska, Agnieszka B., Odzijewicz, Tatiana, Torres, Delfim F.M., Springer, 2015
Expansion formulas in terms of integer-order derivatives for the Hadamard fractional integral and derivative, Shakoor Pooseh, Ricardo Almeida, and Delfim F. M. Torres, Numerical Functional Analysis and Optimization, Vol 33, Issue 3, 2012, pp 301–319.

References

Katugampola, Udita N. (2011). "New approach to a generalized fractional integral". Applied Mathematics and Computation. 218 (3): 860–865. arXiv:1010.0742. doi:10.1016/j.amc.2011.03.062.
Katugampola, Udita N. (2011). On Generalized Fractional Integrals and Derivatives, Ph.D. Dissertation, Southern Illinois University, Carbondale, August, 2011.
Katugampola, Udita N. (2014), "New Approach to Generalized Fractional Derivatives" (PDF), Bull. Math. Anal. App., 6 (4): 1–15, MR 3298307
Katugampola, Udita N. (2015). "Mellin transforms of generalized fractional integrals and derivatives". Applied Mathematics and Computation. 257: 566–580. arXiv:1112.6031. doi:10.1016/j.amc.2014.12.067.
Erdélyi, Arthur (1950–51). "On some functional transformations". Rendiconti del Seminario Matematico dell'Università e del Politecnico di Torino. 10: 217–234. MR 0047818.
Kober, Hermann (1940). "On fractional integrals and derivatives". The Quarterly Journal of Mathematics (Oxford Series). 11 (1): 193–211. Bibcode:1940QJMat..11..193K. doi:10.1093/qmath/os-11.1.193.
Fractional Integrals and Derivatives: Theory and Applications, by Samko, S.; Kilbas, A.A.; and Marichev, O. Hardcover: 1006 pages. Publisher: Taylor & Francis Books. ISBN 2-88124-864-0
Theory and Applications of Fractional Differential Equations, by Kilbas, A. A.; Srivastava, H. M.; and Trujillo, J. J. Amsterdam, Netherlands, Elsevier, February 2006. ISBN 0-444-51832-0
Thaiprayoon, Chatthai; Ntouyas, Sotiris K; Tariboon, Jessada (2015). "On the nonlocal Katugampola fractional integral conditions for fractional Langevin equation". Advances in Difference Equations. 2015. doi:10.1186/s13662-015-0712-3.
Almeida, R.; Bastos, N. (2016). "An approximation formula for the Katugampola integral" (PDF). J. Math. Anal. 7 (1): 23–30. arXiv:1512.03791. Bibcode:2015arXiv151203791A. Archived from the original (PDF) on 2016-03-04. Retrieved 2016-01-02.
Katugampola, Udita. "Google Site". Retrieved 11 November 2017.
Almeida, Ricardo (2017). "Variational Problems Involving a Caputo-Type Fractional Derivative". Journal of Optimization Theory and Applications. 174 (1): 276–294. arXiv:1601.07376. doi:10.1007/s10957-016-0883-4.
Zeng, Sheng-Da; Baleanu, Dumitru; Bai, Yunru; Wu, Guocheng (2017). "Fractional differential equations of Caputo–Katugampola type and numerical solutions". Applied Mathematics and Computations. 315: 549–554. doi:10.1016/j.amc.2017.07.003.
Oliveira, D.S.; Capelas de Oliveira, E. (2017). "Hilfer-Katugampola fractional derivative". arXiv:1705.07733 [math.CA].
Bhairat, Sandeep P.; Dhaigude, D.B. (2017). "Existence and Stability of Fractional Differential Equations Involving Generalized Katugampola Derivative". arXiv:1709.08838 [math.CA].
M. Jleli; D. O'Regan; B. Samet (2016). "On Hermite-Hadamard Type Inequalities via Generalized Fractional Integrals" (PDF). Turkish Journal of Mathematics. 40: 1221–1230. doi:10.3906/mat-1507-79.
Fractional Calculus. An Introduction for Physicists, by Richard Herrmann. Hardcover. Publisher: World Scientific, Singapore; (February 2011) ISBN 978-981-4340-24-3
Odzijewicz, Tatiana; Malinowska, Agnieszka B.; Torres, Delfim F. M. (2012). "Fractional Calculus of Variations in Terms of a Generalized Fractional Integral with Applications to Physics". Abstract and Applied Analysis. 2012: 1–24. arXiv:1203.1961. doi:10.1155/2012/871912.

Pooseh, Shakoor; Almeida, Ricardo; Torres, Delfim F. M. (2012). "Expansion Formulas in Terms of Integer-Order Derivatives for the Hadamard Fractional Integral and Derivative". Numerical Functional Analysis and Optimization. 33 (3): 301. arXiv:1112.0693. doi:10.1080/01630563.2011.647197.

Miller, Kenneth S. (1993). Ross, Bertram (ed.). An Introduction to the Fractional Calculus and Fractional Differential Equations. Wiley. ISBN 0-471-58884-9.
Oldham, Keith B.; Spanier, Jerome (1974). The Fractional Calculus; Theory and Applications of Differentiation and Integration to Arbitrary Order. Mathematics in Science and Engineering. V. Academic Press. ISBN 0-12-525550-0.
Podlubny, Igor (1998). Fractional Differential Equations. An Introduction to Fractional Derivatives, Fractional Differential Equations, Some Methods of Their Solution and Some of Their Applications. Mathematics in Science and Engineering. 198. Academic Press. ISBN 0-12-558840-2.
Herrmann, Richard (2011). Fractional Calculus. An Introduction for Physicists. World Scientific. ISBN 978-981-4340-24-3.
Machado, J.T.; Kiryakova, V.; Mainardi, F. (2011). "Recent history of fractional calculus" (PDF). Communications in Nonlinear Science and Numerical Simulations. 16 (3): 1140. Bibcode:2011CNSNS..16.1140M. doi:10.1016/j.cnsns.2010.05.027. hdl:10400.22/4149. Archived from the original (PDF) on 2013-10-20. Retrieved 2016-01-02.

Notes

The CRONE (R) Toolbox, a Matlab and Simulink Toolbox dedicated to fractional calculus, can be downloaded at http://cronetoolbox.ims-bordeaux.fr

Mathematics Encyclopedia