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| Meta Description | The Laplace transform is an integral transform perhaps second only to the Fourier transform in its utility in solving physical problems. The Laplace transform is particularly useful in solving linear ordinary differential equations such as those arising in the analysis of electronic circuits. The (unilateral) Laplace transform L (not to be confused with the Lie derivative, also commonly denoted L) is defined by L_t[f(t)](s)=int_0^inftyf(t)e^(-st)dt, (1) where f(t) is defined for t>=0... |
| Meta Canonical | null |
| Boilerpipe Text | Algebra
Applied Mathematics
Calculus and Analysis
Discrete Mathematics
Foundations of Mathematics
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History and Terminology
Number Theory
Probability and Statistics
Recreational Mathematics
Topology
Alphabetical Index
New in MathWorld
The Laplace transform is an
integral transform
perhaps second only to the
Fourier transform
in its utility in solving physical problems. The Laplace transform is particularly
useful in solving linear
ordinary differential
equations
such as those arising in the analysis of electronic circuits.
The (unilateral) Laplace transform
(not to be confused with the
Lie
derivative
, also commonly denoted
) is defined by
(1)
where
is defined for
(Abramowitz and Stegun 1972). The unilateral Laplace transform is almost always what
is meant by "the" Laplace transform, although a
bilateral
Laplace transform
is sometimes also defined as
(2)
(Oppenheim
et al.
1997). The unilateral Laplace transform
is implemented in the
Wolfram
Language
as
LaplaceTransform
[
f[t]
,
t
,
s
] and the inverse Laplace transform as
InverseRadonTransform
.
The inverse Laplace transform is known as the
Bromwich integral
, sometimes known as the Fourier-Mellin integral (see also the related
Duhamel's convolution principle).
A table of several important one-sided Laplace transforms is given below.
conditions
1
In the above table,
is the zeroth-order
Bessel function
of the first kind
,
is the
delta function
,
and
is the
Heaviside step function
.
The Laplace transform has many important properties. The Laplace transform existence theorem states that, if
is
piecewise continuous
on every finite interval in
satisfying
(3)
for all
,
then
exists for all
.
The Laplace transform is also
unique
, in the sense that,
given two functions
and
with the same transform so that
(4)
then
Lerch's theorem
guarantees that the integral
(5)
vanishes for all
for a
null function
defined by
(6)
The Laplace transform is
linear
since
(7)
(8)
(9)
The Laplace transform of a
convolution
is given by
(10)
Now consider
differentiation
. Let
be continuously differentiable
times in
. If
, then
(11)
This can be proved by
integration by parts
,
(12)
(13)
(14)
(15)
Continuing for higher-order derivatives then gives
(16)
This property can be used to transform differential equations into algebraic equations, a procedure known as the
Heaviside calculus
,
which can then be inverse transformed to obtain the solution. For example, applying
the Laplace transform to the equation
(17)
gives
(18)
(19)
which can be rearranged to
(20)
If this equation can be inverse Laplace transformed, then the original differential equation is solved.
The Laplace transform satisfied a number of useful properties. Consider
exponentiation
. If
for
(i.e.,
is the Laplace transform of
), then
for
. This follows from
(21)
(22)
(23)
The Laplace transform also has nice properties when applied to
integrals
of functions. If
is
piecewise continuous
and
, then
(24)
See also
Bilateral Laplace Transform
,
Bromwich Integral
,
Fourier-Mellin
Integral
,
Fourier Transform
,
Integral
Transform
,
Laplace-Stieltjes Transform
,
Operational Mathematics
,
Unilateral
Laplace Transform
Explore
this topic in the MathWorld classroom
Explore with Wolfram|Alpha
References
Abramowitz, M. and Stegun, I. A. (Eds.). "Laplace Transforms." Ch. 29 in
Handbook
of Mathematical Functions with Formulas, Graphs, and Mathematical Tables, 9th printing.
New York: Dover, pp. 1019-1030, 1972.
Arfken, G.
Mathematical
Methods for Physicists, 3rd ed.
Orlando, FL: Academic Press, pp. 824-863,
1985.
Churchill, R. V.
Operational
Mathematics.
New York: McGraw-Hill, 1958.
Doetsch, G.
Introduction
to the Theory and Application of the Laplace Transformation.
Berlin: Springer-Verlag,
1974.
Franklin, P.
An
Introduction to Fourier Methods and the Laplace Transformation.
New York:
Dover, 1958.
Graf, U.
Applied
Laplace Transforms and
z
-Transforms for Scientists and Engineers: A Computational
Approach using
a
Mathematica Package.
Basel, Switzerland: Birkhäuser,
2004.
Jaeger, J. C. and Newstead, G. H.
An
Introduction to the Laplace Transformation with Engineering Applications.
London: Methuen, 1949.
Henrici, P.
Applied
and Computational Complex Analysis, Vol. 2: Special Functions, Integral Transforms,
Asymptotics, Continued Fractions.
New York: Wiley, pp. 322-350, 1991.
Krantz,
S. G. "The Laplace Transform." §15.3 in
Handbook
of Complex Variables.
Boston, MA: Birkhäuser, pp. 212-214, 1999.
Morse,
P. M. and Feshbach, H.
Methods
of Theoretical Physics, Part I.
New York: McGraw-Hill, pp. 467-469,
1953.
Oberhettinger, F.
Tables
of Laplace Transforms.
New York: Springer-Verlag, 1973.
Oppenheim,
A. V.; Willsky, A. S.; and Nawab, S. H.
Signals
and Systems, 2nd ed.
Upper Saddle River, NJ: Prentice-Hall, 1997.
Prudnikov,
A. P.; Brychkov, Yu. A.; and Marichev, O. I.
Integrals
and Series, Vol. 4: Direct Laplace Transforms.
New York: Gordon and
Breach, 1992.
Prudnikov, A. P.; Brychkov, Yu. A.; and Marichev,
O. I.
Integrals
and Series, Vol. 5: Inverse Laplace Transforms.
New York: Gordon and
Breach, 1992.
Spiegel, M. R.
Theory
and Problems of Laplace Transforms.
New York: McGraw-Hill, 1965.
Weisstein,
E. W. "Books about Laplace Transforms."
http://www.ericweisstein.com/encyclopedias/books/LaplaceTransforms.html
.
Widder,
D. V.
The
Laplace Transform.
Princeton, NJ: Princeton University Press, 1941.
Zwillinger,
D. (Ed.).
CRC
Standard Mathematical Tables and Formulae.
Boca Raton, FL: CRC Press, pp. 231
and 543, 1995.
Referenced on Wolfram|Alpha
Laplace Transform
Cite this as:
Weisstein, Eric W.
"Laplace Transform."
From
MathWorld
--A Wolfram Resource.
https://mathworld.wolfram.com/LaplaceTransform.html
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- [General Integral Transforms](https://mathworld.wolfram.com/topics/GeneralIntegralTransforms.html)
- [History and Terminology](https://mathworld.wolfram.com/topics/HistoryandTerminology.html)
- [Wolfram Language Commands](https://mathworld.wolfram.com/topics/WolframLanguageCommands.html)
# Laplace Transform
***
[Download Wolfram Notebook](https://mathworld.wolfram.com/notebooks/IntegralTransforms/LaplaceTransform.nb)
The Laplace transform is an [integral transform](https://mathworld.wolfram.com/IntegralTransform.html) perhaps second only to the [Fourier transform](https://mathworld.wolfram.com/FourierTransform.html) in its utility in solving physical problems. The Laplace transform is particularly useful in solving linear [ordinary differential equations](https://mathworld.wolfram.com/OrdinaryDifferentialEquation.html) such as those arising in the analysis of electronic circuits.
The (unilateral) Laplace transform  (not to be confused with the [Lie derivative](https://mathworld.wolfram.com/LieDerivative.html), also commonly denoted ) is defined by
| | |
|---|---|
| =int\_0^inftyf(t)e^(-st)dt, ](https://mathworld.wolfram.com/images/equations/LaplaceTransform/NumberedEquation1.svg) | (1) |
where  is defined for  (Abramowitz and Stegun 1972). The unilateral Laplace transform is almost always what is meant by "the" Laplace transform, although a [bilateral Laplace transform](https://mathworld.wolfram.com/BilateralLaplaceTransform.html) is sometimes also defined as
| | |
|---|---|
| =int\_(-infty)^inftyf(t)e^(-st)dt ](https://mathworld.wolfram.com/images/equations/LaplaceTransform/NumberedEquation2.svg) | (2) |
(Oppenheim *et al.* 1997\). The unilateral Laplace transform ](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline5.svg) is implemented in the [Wolfram Language](http://www.wolfram.com/language/) as [LaplaceTransform](http://reference.wolfram.com/language/ref/LaplaceTransform.html)\[*f\[t\]*, *t*, *s*\] and the inverse Laplace transform as [InverseRadonTransform](http://reference.wolfram.com/language/ref/InverseRadonTransform.html).
The inverse Laplace transform is known as the [Bromwich integral](https://mathworld.wolfram.com/BromwichIntegral.html), sometimes known as the Fourier-Mellin integral (see also the related Duhamel's convolution principle).
A table of several important one-sided Laplace transforms is given below.
| | | |
|---|---|---|
|  | ](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline7.svg) | conditions |
| 1 |  | |
|  |  | |
|  |  |  |
|  |  | ![R\[a\]\>-1](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline16.svg) |
|  |  | |
|  |  |  |
|  |  | ![s\>\|I\[omega\]\|](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline24.svg) |
|  |  | ![s\>\|R\[omega\]\|](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline27.svg) |
|  |  | ![s\>\|I\[omega\]\|](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline30.svg) |
|  |  | ![s\>a+\|I\[b\]\|](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline33.svg) |
|  |  |  |
|  |  | |
|  |  | |
|  |  | |
|  |  |  |
In the above table,  is the zeroth-order [Bessel function of the first kind](https://mathworld.wolfram.com/BesselFunctionoftheFirstKind.html),  is the [delta function](https://mathworld.wolfram.com/DeltaFunction.html), and  is the [Heaviside step function](https://mathworld.wolfram.com/HeavisideStepFunction.html).
The Laplace transform has many important properties. The Laplace transform existence theorem states that, if  is [piecewise continuous](https://mathworld.wolfram.com/PiecewiseContinuous.html) on every finite interval in  satisfying
| | |
|---|---|
|  | (3) |
for all , then ](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline52.svg) exists for all . The Laplace transform is also [unique](https://mathworld.wolfram.com/Unique.html), in the sense that, given two functions  and  with the same transform so that
| | |
|---|---|
| =L\_t\[F\_2(t)\](s)=f(s), ](https://mathworld.wolfram.com/images/equations/LaplaceTransform/NumberedEquation4.svg) | (4) |
then [Lerch's theorem](https://mathworld.wolfram.com/LerchsTheorem.html) guarantees that the integral
| | |
|---|---|
|  | (5) |
vanishes for all  for a [null function](https://mathworld.wolfram.com/NullFunction.html) defined by
| | |
|---|---|
|  | (6) |
The Laplace transform is [linear](https://mathworld.wolfram.com/LinearOperator.html) since
| | | | |
|---|---|---|---|
| ![L\_t\[af(t)+bg(t)\]](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline57.svg) |  | ![int\_0^infty\[af(t)+bg(t)\]e^(-st)dt](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline59.svg) | (7) |
|  |  |  | (8) |
|  |  | ![aL\_t\[f(t)\]+bL\_t\[g(t)\].](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline65.svg) | (9) |
The Laplace transform of a [convolution](https://mathworld.wolfram.com/Convolution.html) is given by
| | |
|---|---|
| ![ L\_t\[f(t)\*g(t)\]=L\_t\[f(t)\]L\_t\[g(t)\] L\_t^(-1)\[FG\]=L\_t^(-1)\[F\]\*L\_t^(-1)\[G\]. ](https://mathworld.wolfram.com/images/equations/LaplaceTransform/NumberedEquation7.svg) | (10) |
Now consider [differentiation](https://mathworld.wolfram.com/Differentiation.html). Let  be continuously differentiable  times in . If , then
| | |
|---|---|
| =s^nL\_t\[f(t)\]-s^(n-1)f(0)-s^(n-2)f^'(0)-...-f^((n-1))(0). ](https://mathworld.wolfram.com/images/equations/LaplaceTransform/NumberedEquation8.svg) | (11) |
This can be proved by [integration by parts](https://mathworld.wolfram.com/IntegrationbyParts.html),
| | | | |
|---|---|---|---|
| ](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline70.svg) |  |  | (12) |
|  |  | ![lim\_(a-\>infty){\[e^(-st)f(t)\]\_0^a+sint\_0^ae^(-st)f(t)dt}](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline75.svg) | (13) |
|  |  | ![lim\_(a-\>infty)\[e^(-sa)f(a)-f(0)+sint\_0^ae^(-st)f(t)dt\]](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline78.svg) | (14) |
|  |  | ![sL\_t\[f(t)\]-f(0).](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline81.svg) | (15) |
Continuing for higher-order derivatives then gives
| | |
|---|---|
| =s^2L\_t\[f(t)\](s)-sf(0)-f^'(0). ](https://mathworld.wolfram.com/images/equations/LaplaceTransform/NumberedEquation9.svg) | (16) |
This property can be used to transform differential equations into algebraic equations, a procedure known as the [Heaviside calculus](https://mathworld.wolfram.com/HeavisideCalculus.html), which can then be inverse transformed to obtain the solution. For example, applying the Laplace transform to the equation
| | |
|---|---|
|  | (17) |
gives
| | |
|---|---|
| -sf(0)-f^'(0)}+a\_1{sL\_t\[f(t)\](s)-f(0)} +a\_0L\_t\[f(t)\](s)=0 ](https://mathworld.wolfram.com/images/equations/LaplaceTransform/NumberedEquation11.svg) | (18) |
| | |
|---|---|
| (s^2+a\_1s+a\_0)-sf(0)-f^'(0)-a\_1f(0)=0, ](https://mathworld.wolfram.com/images/equations/LaplaceTransform/NumberedEquation12.svg) | (19) |
which can be rearranged to
| | |
|---|---|
| =(sf(0)+f^'(0)+a\_1f(0))/(s^2+a\_1s+a\_0). ](https://mathworld.wolfram.com/images/equations/LaplaceTransform/NumberedEquation13.svg) | (20) |
If this equation can be inverse Laplace transformed, then the original differential equation is solved.
The Laplace transform satisfied a number of useful properties. Consider [exponentiation](https://mathworld.wolfram.com/ExponentialFunction.html). If =F(s)](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline82.svg) for  (i.e.,  is the Laplace transform of ), then =F(s-a)](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline86.svg) for . This follows from
| | | | |
|---|---|---|---|
|  |  |  | (21) |
|  |  | ![int\_0^infty\[f(t)e^(at)\]e^(-st)dt](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline93.svg) | (22) |
|  |  | .](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline96.svg) | (23) |
The Laplace transform also has nice properties when applied to [integrals](https://mathworld.wolfram.com/Integral.html) of functions. If  is [piecewise continuous](https://mathworld.wolfram.com/PiecewiseContinuous.html) and , then
| | |
|---|---|
| ![ L\_t\[int\_0^tf(t^')dt^'\]=1/sL\_t\[f(t)\](s). ](https://mathworld.wolfram.com/images/equations/LaplaceTransform/NumberedEquation14.svg) | (24) |
***
## See also
[Bilateral Laplace Transform](https://mathworld.wolfram.com/BilateralLaplaceTransform.html), [Bromwich Integral](https://mathworld.wolfram.com/BromwichIntegral.html), [Fourier-Mellin Integral](https://mathworld.wolfram.com/Fourier-MellinIntegral.html), [Fourier Transform](https://mathworld.wolfram.com/FourierTransform.html), [Integral Transform](https://mathworld.wolfram.com/IntegralTransform.html), [Laplace-Stieltjes Transform](https://mathworld.wolfram.com/Laplace-StieltjesTransform.html), [Operational Mathematics](https://mathworld.wolfram.com/OperationalMathematics.html), [Unilateral Laplace Transform](https://mathworld.wolfram.com/UnilateralLaplaceTransform.html) [Explore this topic in the MathWorld classroom](https://mathworld.wolfram.com/classroom/LaplaceTransform.html)
## Explore with Wolfram\|Alpha

More things to try:
- [vector field](https://www.wolframalpha.com/input/?i=vector+field)
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## References
Abramowitz, M. and Stegun, I. A. (Eds.). "Laplace Transforms." Ch. 29 in *[Handbook of Mathematical Functions with Formulas, Graphs, and Mathematical Tables, 9th printing.](http://www.amazon.com/exec/obidos/ASIN/0486612724/ref=nosim/ericstreasuretro)* New York: Dover, pp. 1019-1030, 1972.
Arfken, G. *[Mathematical Methods for Physicists, 3rd ed.](http://www.amazon.com/exec/obidos/ASIN/0120598760/ref=nosim/ericstreasuretro)* Orlando, FL: Academic Press, pp. 824-863, 1985.
Churchill, R. V. *[Operational Mathematics.](http://www.amazon.com/exec/obidos/ASIN/0070108706/ref=nosim/ericstreasuretro)* New York: McGraw-Hill, 1958.
Doetsch, G. *[Introduction to the Theory and Application of the Laplace Transformation.](http://www.amazon.com/exec/obidos/ASIN/0387064079/ref=nosim/ericstreasuretro)* Berlin: Springer-Verlag, 1974.
Franklin, P. *[An Introduction to Fourier Methods and the Laplace Transformation.](http://www.amazon.com/exec/obidos/ASIN/B0007HQ89I/ref=nosim/ericstreasuretro)* New York: Dover, 1958.
Graf, U.
[Applied Laplace Transforms and *z*\-Transforms for Scientists and Engineers: A Computational Approach using *a* Mathematica Package.](http://www.amazon.com/exec/obidos/ASIN/3764324279/ref=nosim/weisstein-20)
Basel, Switzerland: Birkhäuser, 2004.
Jaeger, J. C. and Newstead, G. H. *[An Introduction to the Laplace Transformation with Engineering Applications.](http://www.amazon.com/exec/obidos/ASIN/041612870X/ref=nosim/ericstreasuretro)* London: Methuen, 1949.
Henrici, P. *[Applied and Computational Complex Analysis, Vol. 2: Special Functions, Integral Transforms, Asymptotics, Continued Fractions.](http://www.amazon.com/exec/obidos/ASIN/047154289X/ref=nosim/ericstreasuretro)* New York: Wiley, pp. 322-350, 1991.
Krantz, S. G. "The Laplace Transform." §15.3 in *[Handbook of Complex Variables.](http://www.amazon.com/exec/obidos/ASIN/0817640118/ref=nosim/ericstreasuretro)* Boston, MA: Birkhäuser, pp. 212-214, 1999.
Morse, P. M. and Feshbach, H. *[Methods of Theoretical Physics, Part I.](http://www.amazon.com/exec/obidos/ASIN/007043316X/ref=nosim/ericstreasuretro)* New York: McGraw-Hill, pp. 467-469, 1953.
Oberhettinger, F. *[Tables of Laplace Transforms.](http://www.amazon.com/exec/obidos/ASIN/0387063501/ref=nosim/ericstreasuretro)* New York: Springer-Verlag, 1973.
Oppenheim, A. V.; Willsky, A. S.; and Nawab, S. H. *[Signals and Systems, 2nd ed.](http://www.amazon.com/exec/obidos/ASIN/0138147574/ref=nosim/ericstreasuretro)* Upper Saddle River, NJ: Prentice-Hall, 1997.
Prudnikov, A. P.; Brychkov, Yu. A.; and Marichev, O. I. *[Integrals and Series, Vol. 4: Direct Laplace Transforms.](http://www.amazon.com/exec/obidos/ASIN/2881248373/ref=nosim/ericstreasuretro)* New York: Gordon and Breach, 1992.
Prudnikov, A. P.; Brychkov, Yu. A.; and Marichev, O. I. *[Integrals and Series, Vol. 5: Inverse Laplace Transforms.](http://www.amazon.com/exec/obidos/ASIN/2881248381/ref=nosim/ericstreasuretro)* New York: Gordon and Breach, 1992.
Spiegel, M. R. *[Theory and Problems of Laplace Transforms.](http://www.amazon.com/exec/obidos/ASIN/007060231X/ref=nosim/ericstreasuretro)* New York: McGraw-Hill, 1965.
Weisstein, E. W. "Books about Laplace Transforms." <http://www.ericweisstein.com/encyclopedias/books/LaplaceTransforms.html>.
Widder, D. V. *[The Laplace Transform.](http://www.amazon.com/exec/obidos/ASIN/0691079927/ref=nosim/ericstreasuretro)* Princeton, NJ: Princeton University Press, 1941.
Zwillinger, D. (Ed.). *[CRC Standard Mathematical Tables and Formulae.](http://www.amazon.com/exec/obidos/ASIN/1584882913/ref=nosim/ericstreasuretro)* Boca Raton, FL: CRC Press, pp. 231 and 543, 1995.
## Referenced on Wolfram\|Alpha
[Laplace Transform](https://www.wolframalpha.com/input/?i=laplace+transform "Laplace Transform")
## Cite this as:
[Weisstein, Eric W.](https://mathworld.wolfram.com/about/author.html) "Laplace Transform." From [*MathWorld*](https://mathworld.wolfram.com/)\--A Wolfram Resource. <https://mathworld.wolfram.com/LaplaceTransform.html>
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The Laplace transform is an [integral transform](https://mathworld.wolfram.com/IntegralTransform.html) perhaps second only to the [Fourier transform](https://mathworld.wolfram.com/FourierTransform.html) in its utility in solving physical problems. The Laplace transform is particularly useful in solving linear [ordinary differential equations](https://mathworld.wolfram.com/OrdinaryDifferentialEquation.html) such as those arising in the analysis of electronic circuits.
The (unilateral) Laplace transform  (not to be confused with the [Lie derivative](https://mathworld.wolfram.com/LieDerivative.html), also commonly denoted ) is defined by
| | |
|---|---|
| =int\_0^inftyf(t)e^(-st)dt, ](https://mathworld.wolfram.com/images/equations/LaplaceTransform/NumberedEquation1.svg) | (1) |
where  is defined for  (Abramowitz and Stegun 1972). The unilateral Laplace transform is almost always what is meant by "the" Laplace transform, although a [bilateral Laplace transform](https://mathworld.wolfram.com/BilateralLaplaceTransform.html) is sometimes also defined as
| | |
|---|---|
| =int\_(-infty)^inftyf(t)e^(-st)dt ](https://mathworld.wolfram.com/images/equations/LaplaceTransform/NumberedEquation2.svg) | (2) |
(Oppenheim *et al.* 1997\). The unilateral Laplace transform ](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline5.svg) is implemented in the [Wolfram Language](http://www.wolfram.com/language/) as [LaplaceTransform](http://reference.wolfram.com/language/ref/LaplaceTransform.html)\[*f\[t\]*, *t*, *s*\] and the inverse Laplace transform as [InverseRadonTransform](http://reference.wolfram.com/language/ref/InverseRadonTransform.html).
The inverse Laplace transform is known as the [Bromwich integral](https://mathworld.wolfram.com/BromwichIntegral.html), sometimes known as the Fourier-Mellin integral (see also the related Duhamel's convolution principle).
A table of several important one-sided Laplace transforms is given below.
| | | |
|---|---|---|
|  | ](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline7.svg) | conditions |
| 1 |  | |
|  |  | |
|  |  |  |
|  |  | ![R\[a\]\>-1](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline16.svg) |
|  |  | |
|  |  |  |
|  |  | ![s\>\|I\[omega\]\|](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline24.svg) |
|  |  | ![s\>\|R\[omega\]\|](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline27.svg) |
|  |  | ![s\>\|I\[omega\]\|](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline30.svg) |
|  |  | ![s\>a+\|I\[b\]\|](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline33.svg) |
|  |  |  |
|  |  | |
|  |  | |
|  |  | |
|  |  |  |
In the above table,  is the zeroth-order [Bessel function of the first kind](https://mathworld.wolfram.com/BesselFunctionoftheFirstKind.html),  is the [delta function](https://mathworld.wolfram.com/DeltaFunction.html), and  is the [Heaviside step function](https://mathworld.wolfram.com/HeavisideStepFunction.html).
The Laplace transform has many important properties. The Laplace transform existence theorem states that, if  is [piecewise continuous](https://mathworld.wolfram.com/PiecewiseContinuous.html) on every finite interval in  satisfying
| | |
|---|---|
|  | (3) |
for all , then ](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline52.svg) exists for all . The Laplace transform is also [unique](https://mathworld.wolfram.com/Unique.html), in the sense that, given two functions  and  with the same transform so that
| | |
|---|---|
| =L\_t\[F\_2(t)\](s)=f(s), ](https://mathworld.wolfram.com/images/equations/LaplaceTransform/NumberedEquation4.svg) | (4) |
then [Lerch's theorem](https://mathworld.wolfram.com/LerchsTheorem.html) guarantees that the integral
| | |
|---|---|
|  | (5) |
vanishes for all  for a [null function](https://mathworld.wolfram.com/NullFunction.html) defined by
| | |
|---|---|
|  | (6) |
The Laplace transform is [linear](https://mathworld.wolfram.com/LinearOperator.html) since
| | | | |
|---|---|---|---|
| ![L\_t\[af(t)+bg(t)\]](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline57.svg) |  | ![int\_0^infty\[af(t)+bg(t)\]e^(-st)dt](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline59.svg) | (7) |
|  |  |  | (8) |
|  |  | ![aL\_t\[f(t)\]+bL\_t\[g(t)\].](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline65.svg) | (9) |
The Laplace transform of a [convolution](https://mathworld.wolfram.com/Convolution.html) is given by
| | |
|---|---|
| ![ L\_t\[f(t)\*g(t)\]=L\_t\[f(t)\]L\_t\[g(t)\] L\_t^(-1)\[FG\]=L\_t^(-1)\[F\]\*L\_t^(-1)\[G\]. ](https://mathworld.wolfram.com/images/equations/LaplaceTransform/NumberedEquation7.svg) | (10) |
Now consider [differentiation](https://mathworld.wolfram.com/Differentiation.html). Let  be continuously differentiable  times in . If , then
| | |
|---|---|
| =s^nL\_t\[f(t)\]-s^(n-1)f(0)-s^(n-2)f^'(0)-...-f^((n-1))(0). ](https://mathworld.wolfram.com/images/equations/LaplaceTransform/NumberedEquation8.svg) | (11) |
This can be proved by [integration by parts](https://mathworld.wolfram.com/IntegrationbyParts.html),
| | | | |
|---|---|---|---|
| ](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline70.svg) |  |  | (12) |
|  |  | ![lim\_(a-\>infty){\[e^(-st)f(t)\]\_0^a+sint\_0^ae^(-st)f(t)dt}](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline75.svg) | (13) |
|  |  | ![lim\_(a-\>infty)\[e^(-sa)f(a)-f(0)+sint\_0^ae^(-st)f(t)dt\]](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline78.svg) | (14) |
|  |  | ![sL\_t\[f(t)\]-f(0).](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline81.svg) | (15) |
Continuing for higher-order derivatives then gives
| | |
|---|---|
| =s^2L\_t\[f(t)\](s)-sf(0)-f^'(0). ](https://mathworld.wolfram.com/images/equations/LaplaceTransform/NumberedEquation9.svg) | (16) |
This property can be used to transform differential equations into algebraic equations, a procedure known as the [Heaviside calculus](https://mathworld.wolfram.com/HeavisideCalculus.html), which can then be inverse transformed to obtain the solution. For example, applying the Laplace transform to the equation
| | |
|---|---|
|  | (17) |
gives
| | |
|---|---|
| -sf(0)-f^'(0)}+a\_1{sL\_t\[f(t)\](s)-f(0)} +a\_0L\_t\[f(t)\](s)=0 ](https://mathworld.wolfram.com/images/equations/LaplaceTransform/NumberedEquation11.svg) | (18) |
| | |
|---|---|
| (s^2+a\_1s+a\_0)-sf(0)-f^'(0)-a\_1f(0)=0, ](https://mathworld.wolfram.com/images/equations/LaplaceTransform/NumberedEquation12.svg) | (19) |
which can be rearranged to
| | |
|---|---|
| =(sf(0)+f^'(0)+a\_1f(0))/(s^2+a\_1s+a\_0). ](https://mathworld.wolfram.com/images/equations/LaplaceTransform/NumberedEquation13.svg) | (20) |
If this equation can be inverse Laplace transformed, then the original differential equation is solved.
The Laplace transform satisfied a number of useful properties. Consider [exponentiation](https://mathworld.wolfram.com/ExponentialFunction.html). If =F(s)](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline82.svg) for  (i.e.,  is the Laplace transform of ), then =F(s-a)](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline86.svg) for . This follows from
| | | | |
|---|---|---|---|
|  |  |  | (21) |
|  |  | ![int\_0^infty\[f(t)e^(at)\]e^(-st)dt](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline93.svg) | (22) |
|  |  | .](https://mathworld.wolfram.com/images/equations/LaplaceTransform/Inline96.svg) | (23) |
The Laplace transform also has nice properties when applied to [integrals](https://mathworld.wolfram.com/Integral.html) of functions. If  is [piecewise continuous](https://mathworld.wolfram.com/PiecewiseContinuous.html) and , then
| | |
|---|---|
| ![ L\_t\[int\_0^tf(t^')dt^'\]=1/sL\_t\[f(t)\](s). ](https://mathworld.wolfram.com/images/equations/LaplaceTransform/NumberedEquation14.svg) | (24) |
***
## See also
[Bilateral Laplace Transform](https://mathworld.wolfram.com/BilateralLaplaceTransform.html), [Bromwich Integral](https://mathworld.wolfram.com/BromwichIntegral.html), [Fourier-Mellin Integral](https://mathworld.wolfram.com/Fourier-MellinIntegral.html), [Fourier Transform](https://mathworld.wolfram.com/FourierTransform.html), [Integral Transform](https://mathworld.wolfram.com/IntegralTransform.html), [Laplace-Stieltjes Transform](https://mathworld.wolfram.com/Laplace-StieltjesTransform.html), [Operational Mathematics](https://mathworld.wolfram.com/OperationalMathematics.html), [Unilateral Laplace Transform](https://mathworld.wolfram.com/UnilateralLaplaceTransform.html) [Explore this topic in the MathWorld classroom](https://mathworld.wolfram.com/classroom/LaplaceTransform.html)
## Explore with Wolfram\|Alpha
## References
Abramowitz, M. and Stegun, I. A. (Eds.). "Laplace Transforms." Ch. 29 in *[Handbook of Mathematical Functions with Formulas, Graphs, and Mathematical Tables, 9th printing.](http://www.amazon.com/exec/obidos/ASIN/0486612724/ref=nosim/ericstreasuretro)* New York: Dover, pp. 1019-1030, 1972.Arfken, G. *[Mathematical Methods for Physicists, 3rd ed.](http://www.amazon.com/exec/obidos/ASIN/0120598760/ref=nosim/ericstreasuretro)* Orlando, FL: Academic Press, pp. 824-863, 1985.Churchill, R. V. *[Operational Mathematics.](http://www.amazon.com/exec/obidos/ASIN/0070108706/ref=nosim/ericstreasuretro)* New York: McGraw-Hill, 1958.Doetsch, G. *[Introduction to the Theory and Application of the Laplace Transformation.](http://www.amazon.com/exec/obidos/ASIN/0387064079/ref=nosim/ericstreasuretro)* Berlin: Springer-Verlag, 1974.Franklin, P. *[An Introduction to Fourier Methods and the Laplace Transformation.](http://www.amazon.com/exec/obidos/ASIN/B0007HQ89I/ref=nosim/ericstreasuretro)* New York: Dover, 1958.Graf, U. [Applied Laplace Transforms and *z*\-Transforms for Scientists and Engineers: A Computational Approach using *a* Mathematica Package.](http://www.amazon.com/exec/obidos/ASIN/3764324279/ref=nosim/weisstein-20) Basel, Switzerland: Birkhäuser, 2004.Jaeger, J. C. and Newstead, G. H. *[An Introduction to the Laplace Transformation with Engineering Applications.](http://www.amazon.com/exec/obidos/ASIN/041612870X/ref=nosim/ericstreasuretro)* London: Methuen, 1949.Henrici, P. *[Applied and Computational Complex Analysis, Vol. 2: Special Functions, Integral Transforms, Asymptotics, Continued Fractions.](http://www.amazon.com/exec/obidos/ASIN/047154289X/ref=nosim/ericstreasuretro)* New York: Wiley, pp. 322-350, 1991.Krantz, S. G. "The Laplace Transform." §15.3 in *[Handbook of Complex Variables.](http://www.amazon.com/exec/obidos/ASIN/0817640118/ref=nosim/ericstreasuretro)* Boston, MA: Birkhäuser, pp. 212-214, 1999.Morse, P. M. and Feshbach, H. *[Methods of Theoretical Physics, Part I.](http://www.amazon.com/exec/obidos/ASIN/007043316X/ref=nosim/ericstreasuretro)* New York: McGraw-Hill, pp. 467-469, 1953.Oberhettinger, F. *[Tables of Laplace Transforms.](http://www.amazon.com/exec/obidos/ASIN/0387063501/ref=nosim/ericstreasuretro)* New York: Springer-Verlag, 1973.Oppenheim, A. V.; Willsky, A. S.; and Nawab, S. H. *[Signals and Systems, 2nd ed.](http://www.amazon.com/exec/obidos/ASIN/0138147574/ref=nosim/ericstreasuretro)* Upper Saddle River, NJ: Prentice-Hall, 1997.Prudnikov, A. P.; Brychkov, Yu. A.; and Marichev, O. I. *[Integrals and Series, Vol. 4: Direct Laplace Transforms.](http://www.amazon.com/exec/obidos/ASIN/2881248373/ref=nosim/ericstreasuretro)* New York: Gordon and Breach, 1992.Prudnikov, A. P.; Brychkov, Yu. A.; and Marichev, O. I. *[Integrals and Series, Vol. 5: Inverse Laplace Transforms.](http://www.amazon.com/exec/obidos/ASIN/2881248381/ref=nosim/ericstreasuretro)* New York: Gordon and Breach, 1992.Spiegel, M. R. *[Theory and Problems of Laplace Transforms.](http://www.amazon.com/exec/obidos/ASIN/007060231X/ref=nosim/ericstreasuretro)* New York: McGraw-Hill, 1965.Weisstein, E. W. "Books about Laplace Transforms." <http://www.ericweisstein.com/encyclopedias/books/LaplaceTransforms.html>.Widder, D. V. *[The Laplace Transform.](http://www.amazon.com/exec/obidos/ASIN/0691079927/ref=nosim/ericstreasuretro)* Princeton, NJ: Princeton University Press, 1941.Zwillinger, D. (Ed.). *[CRC Standard Mathematical Tables and Formulae.](http://www.amazon.com/exec/obidos/ASIN/1584882913/ref=nosim/ericstreasuretro)* Boca Raton, FL: CRC Press, pp. 231 and 543, 1995.
## Referenced on Wolfram\|Alpha
[Laplace Transform](https://www.wolframalpha.com/input/?i=laplace+transform "Laplace Transform")
## Cite this as:
[Weisstein, Eric W.](https://mathworld.wolfram.com/about/author.html) "Laplace Transform." From [*MathWorld*](https://mathworld.wolfram.com/)\--A Wolfram Resource. <https://mathworld.wolfram.com/LaplaceTransform.html>
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