On the Agaciro Equation via the Scope of Green Function

We have undertaken an investigation of a kind of third-order equation called Agaciro equation within the folder of both integer and fractional order derivative. In the way of deriving the general exact solution of this equation, we employed the philosophy of the Green function together with some integral transform operators and special functions including but not limited to the Laplace, Fourier, and Mellin transform. We presented some examples of exact solution of this class of third-order equations for integer and fractional order derivative. It is important to point out that the value of Agaciro equation can be extended to describe assorted phenomenon in sciences.


Introduction
An important method used in the field of partial and ordinary linear is Green function method.It is important to remember that the construction of the Green function is an art and difficult exercise because, in the way of construction, one must first make sure of the existence and the uniqueness of this function, which is a whole topic in mathematics.Once the uniqueness and the existence are insured, one needs to have a knowledge of methods of solving either partial differential equations or ordinary differential equations, again this is a whole topic on its own in mathematics.Within the scope of fractional calculus, one further needs a clear knowledge of special function and other useful integral transform operators including but not limited to Laplace transform, Fourier transform, and Mellin transform.This method was recently extended to the scope of partial and ordinary differential equations with noninteger order derivative [1,2].It should be mentioned that the finding of the Green function in the folder of the fractional calculus is very difficult because this involves at the same time some special functions and also some integral transform, for instance the Mellin, the Laplace, and the Fourier transform operators.It is perhaps important to present a brief history regarding the Green function method.
In mathematical sciences and related disciplines, a Green function is the desired answer of an inhomogeneous differential equation defined on a domain, with particular preliminary conditions or boundary conditions.By means of the superposition theory, the convolution of a Green function with a subjective function () on that domain is the solution to the inhomogeneous differential equation for the unknown function ().These classes of functions are named after the British mathematician George Green, who first developed the concept in the year 1830 [3,4].In the contemporary study of linear partial differential equations, Green's functions are revised for the most part from the standpoint of the original solutions as a replacement is significant to also draw attention to the fact that, under many-folders theories, the concept is employed in physics, more importantly in quantum field theory, aerodynamics, aeroacoustics, electrodynamics, and statistical field theory, to downgrade to an assortment of types of correlations functions, still those that do not able-bodied mathematical explanation.=  (, , ) , 0 < , ,  ≤ 1. (1) We will examine two cases: the case where the orders of the derivative are integer numbers meaning  =  =  = 1 and the case where 0 < , ,  < 1.

Some Useful Information about Fractional Derivative
With the purpose to provide lodgings to readers that are not in the field of fractional calculus, we dedicate this subdivision to the symposium supporting the fundamental principle of the fractional calculus.But we will much stress on the properties of the Caputo fractional derivative since it will be used throughout the remainder of the paper.
Definition 1 (Riemann-Liouville integral [5][6][7][8][9][10]).The Riemann-Liouville integral gives the orthodox outward appearance of fractional calculus.The theory for intermittent functions consequently including the "boundary condition" of repeating after a period is the Weyl integral.The Riemann-Liouville integral of order  of a function () is given by Definition 2 (Caputo fractional derivative).There is one more option for working out the definition of fractional derivation: Caputo established it in 1967 in his paper [11].Quite the opposite of the Riemann Liouville fractional derivative, when getting to the bottom of differential equations by means of Caputo's definition, it is not indispensable to describe the fractional order initial conditions.Caputo's definition is illustrated as follows: The above definitions are frequently used in pure and applied mathematics.
Definition 3. The Laplace transform is an extensively used integral transform in the midst of numerous applications in physics and engineering.The Laplace transform of the function  is defined as follows: Let us observe the Laplace transform of the fractional derivative with Caputo: The above uses the usual initial conditions or values of the functions.
Another useful property of the Caputo derivative is the following: where Γ is the gamma function defined as The Fourier transform of a function () of real variable  is defined as The Fourier transform of a fractional derivative of order  is The Mellin transform of a function () of a real variable  ∈ R + is defined as

Construction of Green Function
We will devote this section to the symposium supporting the construction of the Green function of the nonhomogeneous Agaciro equation ( 1); this will be achieved via some wellknown integral operator transform.The general equation under analysis here is given as

Green Function for Agaciro Equation.
We will present the general solution of the Agaciro equation when  =  =  = 1.To solve this equation, we make use of two integral transforms: in -direction, we apply the Laplace transform and in --direction, we apply the Fourier transform.
The general Green function associated with the Agaciro equation is given as To find the Green function, it will perhaps be important to revert the denominator of the above to the suitable form that will allow the inversion of the two operators; thus, one can see that the denominator can be factorised as follows: . ( With this new version in hand it is possible for us to conclude that the Green function for the Agaciro equation is given as For the sake of simplicity, let us put ))) , ))) . ( Then we observe that Therefore, the following relationship can be established: The above solution is the exact solution to Agaciro equation.We will in the next subsection present some examples of exact solution of Agaciro equation.

Exact Analytical Solution of Some Agaciro Equations
with initial condition where expIntegralEi [] is the exponential integral defined as expIntegralEi and erf[] is the error function defined as To obtain the exact solution to (26) and ( 27), we apply on both sides of ( 22 ( together with initial condition where Bessel [1, 𝑥] is the Bessel function of first kind and is defined as To obtain the exact solution to (32) and (33), we apply on both sides of (33) the double Fourier-Laplace operator as offered earlier, and then we obtain the desired Green function With the above Green function in hand and making use of the initial condition equation ( 21), we can now obtain straightforward the following solution: This is the exact solution of the nonhomogeneous Agaciro equation (32).

Green Function of Space-Time Fractional Agaciro Equation
We devote this section to the symposium supporting the construction of the Green function for the space-time fractional Agaciro equation ( 1 (37) The construction of this Green function will be achieved via the application of the double Fourier-Laplace operator as follows.Therefore applying the Laplace on both sides of (1), we arrive at the following equation: Now if we affect the double Fourier transform on both sides of the above equation, meaning we apply the Fourier transform in  and  direction, we obtain the following homogeneous equation: The broad-spectrum fractional Green function that connects to the space-time fractional Agaciro equation is provided as It is perhaps important to point out that the below equation is the fractional characteristic equation associate to the spacetime fractional Agaciro equation: To discover the Green function, it will conceivably relapse the above fractional polynomial equation to the appropriate form that will consent to the inversion of the two operators; consequently, one can see that the denominator can be factorised as follows: In order to find the inverse of the above equation, we will first accommodate readers that are not used to relationships between some special functions and some properties of Fourier and Laplace transforms.An important special function in the field of fractional calculus is the Mittag-Leffler function which is regarded as the generalized exponential function and is defined as ))) = −  (, , ) . (49) , , ) +     (, , ) +     (, , ) +     (, , ) −  (, , ) =  (, , ) , 0 < , ,  ≤ 1.

3. 3 .
Analytical Results of the Agaciro Equations.We present in this section the numerical results of the nonhomogeneous Agaciro equation as function of time and space.The numerical results have been depicted in Figures 1, 2, 3, and 4.

2
Mathematical Problems in EngineeringIn this present work we will present the discussion underpinning the construction of Green function of a novel equation called "Agaciro" equation presented as (, , ) −   (, , ) =   (, , ) .