Katugampola Fractional Operators

In mathematics, Katugampola fractional operators are integral operators that generalize the ''Riemann–Liouville'' and the ''Hadamard'' fractional operators into a unique form.Katugampola, Udita N. (2011).
On Generalized Fractional Integrals and Derivatives
Ph.D. Dissertation, Southern Illinois University, Carbondale, August, 2011. 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''Fractional Integrals and Derivatives: Theory and Applications'', by Samko, S.; Kilbas, A.A.; and Marichev, O. Hardcover: 1006 pages. Publisher: Taylor & Francis Books. ''Theory and Applications of Fractional Differential Equations'', by Kilbas, A. A.; Srivastava, H. M.; and Trujillo, J. J. Amsterdam, Netherlands, Elsevier, February 2006. 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 $\textit^p_c(a,b), \; c\in \mathbb, \, 1 \leq p \leq \infty$ be the space of those Lebesgue measurable functions $f$ on $$, b for which $\, f\, _ < \infty$, where the norm is defined by
$\begin \, f\, _ =\left(\int^b_a , t^c f(t), ^p \frac\right)^ < \infty, \end$
for $1 \leq p < \infty,\, c \in \mathbb$ and for the case $p=\infty$
\begin
\, f\, _ = \text_ f(t), \quad ( c \in \mathbb).
\end

Katugampola fractional integral

It is defined via the following integrals

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

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

These are the fractional generalizations of the $n$-fold left- and right-integrals of the form

: $\int_a^x t_1^ \, dt_1 \int_a^ t_2^ \,dt_2 \cdots \int_a^ t_n^ f(t_n)\,dt_n$

and

: $\int_x^b t_1^ \,dt_1 \int^b_ t_2^ \,dt_2 \cdots \int^b_ t_n^ f(t_n) \, dt_n$ for $\textstyle n \in \mathbb,$

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,\ \operatorname(\alpha) \geq 0, n= operatorname(\alpha)1 and $\rho >0.$ The generalized fractional derivatives, corresponding to the generalized fractional integrals () and () are defined, respectively, for $0 \leq a < x < b \leq \infty$, by


:$\begin \big(^\rho \mathcal^\alpha_f\big)(x)&= \bigg(x^ \,\frac\bigg)^n\,\, \big(^\rho \mathcal^_f\big)(x)\\ &= \frac \, \bigg(x^ \,\frac\bigg)^n \int^x_a \frac\, d\tau, \end$
and
:$\begin \big(^\rho \mathcal^\alpha_f\big)(x) &= \bigg(-x^ \,\frac\bigg)^n\,\, \big(^\rho \mathcal^_f\big)(x)\\ &= \frac\bigg(-x^\frac\bigg)^n \int^b_x\frac\, d\tau, \end$
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 $f \in L^1$, b \alpha \in (0, 1] and $\rho$. The C-K fractional derivative of order $\alpha$ of the function f: ,b\rightarrow \mathbb, with respect to parameter $\rho$ can be expressed as

: ^C\mathcal^_f(t)=\frac\frac\int^t_a\frac\big (s)-f(a)\big,ds.

It satisfies the following result. Assume that $f \in C^1$, b , then the C-K derivative has the following equivalent form
::$^C\mathcal^_f(t)=\frac\int^t_a \fracds.$

Hilfer–Katugampola fractional derivative

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

:$\begin (\varphi)(x)&=\left(\pm\,\left(t^\frac\right)\varphi\right)(x)\\ &=\left(\pm\,\delta_\,\varphi\right)(x), \end$
where $\delta_= t^\frac$, for functions $\varphi$ in which the expression on the right hand side
exists, where $\mathcal$ is the generalized fractional integral
given in ().

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 $\alpha \in \mathcal,\ \operatorname(\alpha) > 0,$ and $\rho >0.$ Then,
$\begin & \mathcal\bigg(^\rho \mathcal^\alpha_f\bigg)(s) = \frac\, \mathcalf(s + \alpha\rho), \quad \operatorname(s/\rho + \alpha) < 1, \, x > a, \\ & \mathcal\bigg(^\rho \mathcal^\alpha_f\bigg)(s) = \frac\, \mathcalf(s + \alpha\rho), \quad \operatorname(s/\rho) > 0, \, x < b, \end$

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

Hermite-Hadamard type inequalities

Katugampola operators satisfy the following Hermite-Hadamard type inequalities:

Theorem

Let $\alpha > 0$ and $\rho > 0$. If $f$ is a convex function on $$, b, then

f\left(\frac\right) \leq \frac\left \rho \mathcal^\alpha_F(b)+^\rho \mathcal^\alpha_F(a)\right\leq \frac,

where $F(x) = f(x) + f(a+b-x), \; x \in$, b/math>.

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 $$, b, then

f\left(\frac\right) \leq \frac\left \mathbf^\alpha_F(b)+ \mathbf^\alpha_F(a)\right\leq \frac,

where $\mathbf^\alpha_$ and $\mathbf^\alpha_$ 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

Further reading

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Notes

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

Fractional calculus