PlanetMath (more info)
 Math for the people, by the people. Sponsor PlanetMath
Encyclopedia | Requests | Forums | Docs | Wiki | Random | RSS  
Login
create new user
name:
pass:
forget your password?
Main Menu
Owner confidence rating: Very high Entry average rating: No information on entry rating
[parent] table of Laplace transforms (Feature)

Below are tables of Laplace transforms; one lists some of the common properties, and the other lists some common examples.

Properties

Original Transformed comment derivation
$af(t)+bg(t)$ $a\mathcal{L}\{f(t)\}+b\mathcal{L}\{g(t)\}$ linearity  
$f(t)*g(t)$ $\mathcal{L}\{f(t)\}\mathcal{L}\{g(t)\}$ convolution property here
$\displaystyle{\int_a^bf(t,\,x)\,dx}$ $\displaystyle{\int_a^b\mathcal{L}\{f(t,\,x)\}\,dx}$ integration with respect to a parametre here
$\displaystyle{\frac{\partial}{\partial x}f(t,\,x)}$ $\displaystyle{\frac{\partial}{\partial x}\mathcal{L}\{f(t,\,x)\}}$ diffentiation with respect to a parameter  
$f(\displaystyle{\frac{t}{a}})$ $aF(as)$ $\mathcal{L}\{f(t)\} = F(s)$ here
$e^{at}f(t)$ $F(s-a)$ $\mathcal{L}\{f(t)\} = F(s)$ here
$f(t-a)$ $e^{-as}F(s)$ $\mathcal{L}\{f(t)\} = F(s)$ here
$t^nf(t)$ $(-1)^nF^{(n)}(s)$ $\mathcal{L}\{f(t)\} = F(s)$ here
$\displaystyle\frac{f(t)}{t}$ $\displaystyle\int_s^\infty F(u)\,du$ $\mathcal{L}\{f(t)\} = F(s)$ here
$\displaystyle{\int_0^tf(u)\,du}$ $\displaystyle{\frac{F(s)}{s}}$ $\mathcal{L}\{f(t)\} = F(s)$ here
$f'(t)$ $sF(s)-\lim_{x\to0+}f(x)$ $\mathcal{L}\{f(t)\} = F(s)$ here
$f''(t)$ $s^2F(s)-s\lim_{x\to0+}f'(x)-\lim_{x\to0+}f(x)$ $\mathcal{L}\{f(t)\} = F(s)$  

Examples

$f(t)$ $\mathcal{L}\{f(t)\}$ conditions explanation derivation
$e^{at}$ $\displaystyle{\frac{1}{s-a}}$ $s>a$   trivial
$\cos{at}$ $\displaystyle{\frac{s}{s^{2}+a^{2}}}$ $s>0$   here
$\sin{at}$ $\displaystyle{\frac{a}{s^{2}+a^{2}}}$ $s>0$   here
$\cosh{at}$ $\displaystyle{\frac{s}{s^{2}-a^{2}}}$ $s>|a|$   here
$\sinh{at}$ $\displaystyle{\frac{a}{s^{2}-a^{2}}}$ $s>|a|$   here
$\displaystyle\frac{\sin{t}}{t}$ $\displaystyle\arctan\frac{1}{s}$ $s>0$ See sinc function here
$t^r$ $\displaystyle{\frac{\Gamma(r+1)}{s^{r+1}}}$ $r>-1,\;\;s>0$ gamma function $\Gamma$ here
$\displaystyle e^{a^2t}\,{\rm erf}\,a\sqrt{t}$ $\displaystyle\frac{a}{(s\!-\!a^2)\sqrt{s}}$ $s>a^2$ See error function here
$\displaystyle e^{a^2t}\,{\rm erfc}\,a\sqrt{t}$ $\displaystyle\frac{1}{(a\!+\!\sqrt{s})\sqrt{s}}$ $s>0$ See error function here
$\displaystyle\frac{1}{\sqrt{t}}$ $\displaystyle\sqrt{\frac{\pi}{s}}$ $s>0$   here
$J_0(at)$ $\displaystyle\frac{1}{\sqrt{s^2+a^2}}$ $s>0$ Bessel function $J_0$ here
$e^{-t^2}$ $\displaystyle\frac{\sqrt{\pi}}{2}e^\frac{s^2}{4}\mathrm{erfc}\Big(\frac{s}{2}\Big)$ $s>0$ See error function here
$\ln{t}$ $\displaystyle-\frac{\gamma+\ln{s}}{s}$ $s>0$ Euler'sconstant $\gamma$ here
$\delta(t)$ $1$   Dirac delta function  

Rational Functions

$f(t)$ $\mathcal{L}\{f(t)\}$ conditions explanation derivation
1 $\displaystyle{1 \over s}$      
$t$ $\displaystyle{1 \over s^2}$     here
$\displaystyle{t^{n-1} \over (n-1)!}$ $\displaystyle{1 \over s^n}$     here
$\displaystyle{1 \over t+a}$ $e^{as} {\rm E}_1(as)$ $a > 0$ exponential integral ${\rm E}_1$ here
$\displaystyle{1 \over (t+a)^2}$ $\displaystyle{1 \over a}-se^{as}{\rm E}_1(as)$ $a > 0$   here
$\displaystyle{1 \over (t+a)^n}$ $a^{1-n} e^{as} E_n (as)$ $a > 0,\;\; n \in \mathbb{N}$ ?  
$L_n(t)$ $\displaystyle\frac{1}{s}\!\left(\!\frac{s-1}{s}\!\right)^n$ $s > 0$ Laguerre polynomial $L_n$  




Anyone with an account can edit this entry. Please help improve it!

"table of Laplace transforms" is owned by CWoo. [ full author list (3) ]
(view preamble | get metadata)

View style:

See Also: Laplace transform of sine integral, telegraph equation, inverse Laplace transform of derivatives, table of integrals, using Laplace transform to solve initial value problems, rules for Laplace transform, exponential integral, integration of Laplace transform with respect to parameter, Laplace transform of periodic functions


This object's parent.
Log in to rate this entry.
(view current ratings)

Cross-references: Laguerre polynomial, exponential integral, Dirac delta function, Euler's, Bessel function, error function, gamma function, sinc function, parametre, convolution, derivation, properties
There are 6 references to this entry.

This is version 46 of table of Laplace transforms, born on 2008-05-14, modified 2009-07-11.
Object id is 10588, canonical name is TableOfLaplaceTransforms.
Accessed 2518 times total.

Classification:
AMS MSC44A10 (Integral transforms, operational calculus :: Laplace transform)

Pending Errata and Addenda
None.
[ View all 1 ]
Discussion
Style: Expand: Order:
forum policy

No messages.

Interact
post | correct | update request | add example | add (any)