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mathematical analysis Analysis is the branch of mathematics dealing with continuous functions, limit (mathematics), limits, and related theories, such as Derivative, differentiation, Integral, integration, measure (mathematics), measure, infinite sequences, series (m ...
, initialization of the differintegrals is a topic in
fractional calculus Fractional calculus is a branch of mathematical analysis that studies the several different possibilities of defining real number powers or complex number powers of the differentiation operator D :D f(x) = \frac f(x)\,, and of the integration o ...
.


Composition rule of Differintegrals

The composition law of the
differintegral In fractional calculus, an area of mathematical analysis, the differintegral (sometime also called the derivigral) is a combined differentiation/integration operator. Applied to a function ƒ, the ''q''-differintegral of ''f'', here denoted by ...
operator states that although: \mathbb^q\mathbb^ = \mathbb wherein ''D''−''q'' is the left
inverse Inverse or invert may refer to: Science and mathematics * Inverse (logic), a type of conditional sentence which is an immediate inference made from another conditional sentence * Additive inverse (negation), the inverse of a number that, when ad ...
of ''Dq'', the converse is not necessarily true: :\mathbb^\mathbb^q \neq \mathbb


Example

Consider elementary integer-order
calculus Calculus, originally called infinitesimal calculus or "the calculus of infinitesimals", is the mathematics, mathematical study of continuous change, in the same way that geometry is the study of shape, and algebra is the study of generalizati ...
. Below is an integration and differentiation using the example function 3x^2+1: :\frac\left int (3x^2+1)dx\right= \frac
^3+x+C In arithmetic and algebra, the cube of a number is its third power, that is, the result of multiplying three instances of together. The cube of a number or any other mathematical expression is denoted by a superscript 3, for example or . ...
= 3x^2+1\,, Now, on exchanging the order of composition: :\int \left frac(3x^2+1)\right= \int 6x \,dx = 3x^2+C\,, Where ''C is'' the
constant of integration In calculus, the constant of integration, often denoted by C (or c), is a constant term added to an antiderivative of a function f(x) to indicate that the indefinite integral of f(x) (i.e., the set of all antiderivatives of f(x)), on a connect ...
. Even if it was not obvious, the initialized condition ''ƒ'''(0) = ''C'', ''ƒ''''(0) = ''D'', etc. could be used. If we neglected those initialization terms, the last equation would show the composition of integration then differentiation (and vice versa) would not hold.


Description of initialization

Working with a properly initialized differ integral is the subject of initialized fractional calculus. If the differ integral is initialized properly, then the hoped-for composition law holds. The problem is that in differentiation, information is lost, as with ''C'' in the first equation. However, in fractional calculus, given that the operator has been fractionalized and is thus continuous, an entire complementary function is needed. This is called complementary function \Psi. :\mathbb^q_t f(t) = \frac\frac\int_0^t (t-\tau)^f(\tau)\,d\tau + \Psi(x)


See also

*
Initial conditions In mathematics and particularly in dynamic systems, an initial condition, in some contexts called a seed value, is a value of an evolving variable at some point in time designated as the initial time (typically denoted ''t'' = 0). F ...
*
Dynamical systems In mathematics, a dynamical system is a system in which a function describes the time dependence of a point in an ambient space. Examples include the mathematical models that describe the swinging of a clock pendulum, the flow of water in ...


References

* (technical report). {{DEFAULTSORT:Initialized Fractional Calculus Fractional calculus