Inverse Laplace Transform Of A Constant
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Inverse Laplace Transform Of A Constant
The Laplace transform is a widely used integral transform with many applications in physics
and engineering. Denoted , it is a linear operator of a function f(t) with a real argument t (t 0)
that transforms it to a function F(s) with a complex argument s.
This transformation is essential y bijective for the majority of practical uses; the respective
pairs of f(t) and F(s) are matched in tables.
The Laplace transform has the useful property that many relationships and operations over
the originals f(t) correspond to simpler relationships and operations over the images F(s).
It is named after PierreSimon Laplace, who introduced the transform in his work on
probability theory. The Laplace transform is related to the Fourier transform, but whereas the
Fourier transform expresses a function or signal as a series of modes of vibration
(frequencies), the Laplace transform resolves a function into its moments.
Like the Fourier transform, the Laplace transform is used for solving differential and integral
equations. In physics and engineering it is used for analysis of linear timeinvariant systems
such as electrical circuits, harmonic oscil ators, optical devices, and mechanical systems.
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In such analyses, the Laplace transform is often interpreted as a transformation from the
timedomain, in which inputs and outputs are functions of time, to the frequencydomain,
where the same inputs and outputs are functions of complex angular frequency, in radians per
unit time.
Given a simple mathematical or functional description of an input or output to a system, the
Laplace transform provides an alternative functional description that often simplifies the
process of analyzing the behavior of the system, or in synthesizing a new system based on a
set of specifications.
We can find inverse Laplace Transform of a constant function very easily we need to have
knowledge about Laplace transform. Laplace transform has a wide application in mathematics
but it is mainly used in Integration.
The main application of Laplace transform is to convert frequency domain signal to time
domain signal .here we wil see an example how we can find the inverse Laplace transform of
a constant function.
Example 1: Find the inverse transform of F(S) = (S+2)(S+4)/ S2+S?
Solution: For solving this type of problem we need to fol ow some steps given below.
Step 1: For converting this in to inverse Laplace transform we wil see if we can factorize the
denominator of the function.
So we can write S2+S as S(S+1) now we can rewrite the equation as (S+2)(S+4)/S(S+1).
Step 2: Now we will write the equation in partial fraction form as,
(S+2)(S+4)/S(S+1) = A/S + B/S+1,
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Now our task is to find the value of constant `A' and `B' for that we need to apply cover up
method with the help of this method we can find the value of constant very simply just need to
have knowledge about solving fraction.
The set of values for which F(s) converges absolutely is either of the form Re{s} > a or else
Re{s} a, where a is an extended real constant,  a . (This follows from the dominated
convergence theorem.) The constant a is known as the abscissa of absolute convergence,
and depends on the growth behavior of (t).
Analogously, the twosided transform converges absolutely in a strip of the form a < Re{s} < b,
and possibly including the lines Re{s} = a or Re{s} = b.[10] The subset of values of s for which
the Laplace transform converges absolutely is cal ed the region of absolute convergence or
the domain of absolute convergence. In the twosided case, it is sometimes cal ed the strip of
absolute convergence.
The Laplace transform is analytic in the region of absolute convergence. Similarly, the set of
values for which F(s) converges (conditionally or absolutely) is known as the region of
conditional convergence, or simply the region of convergence (ROC). If the Laplace transform
converges (conditionally) at s = s0, then it automatical y converges for all s with Re{s} >
Re{s0}.
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