System Dynamics

Laplace transforms

is a table with functions of time \(f(t)\) on the left and corresponding Laplace transforms \(L(s)\) on the right. Where applicable, \(s = \sigma + j \omega\) is the Laplace transform variable, \(T\) is the time-domain period, \(\omega_0 2\pi/T\) is the corresponding angular frequency, \(j = \sqrt{-1}\), \(a \in \mathbb{R}^+\), and \(b, t_0 \in \mathbb{R}\) are constants.

Function of time \(t\) Function of complex frequency \(s\)
\(a_1 f_1(t) + a_2 f_2(t)\) \(a_1 F_1(s) + a_2 F_2(s)\)
\(f(t-t_0)\) \(F(s) e^{-t_0 s}\)
\(f'(t)\) \(s F(s) - f(0)\)
\(\dfrac{d^n f(t)}{d t^n}\) \(s^n F(s) + s^{(n-1)} f(0) + s^{(n-2)} f'(0) + \cdots + f^{(n-1)}(0)\)
\(\displaystyle\int_0^t f(\tau) d\tau\) \(\dfrac{1}{s} F(s)\)
\(t f(t)\) \(-F'(s)\)
\(f_1(t) * f_2(t) = \displaystyle\int_{-\infty}^\infty f_1(\tau) f_2(t - \tau) d\tau\) \(F_1(s) F_2(s)\)
\(\delta(t)\) \(1\)
\(u_s(t)\) \(1/s\)
\(u_r(t)\) \(1/s^2\)
\(t^{n-1}/(n-1)!\) \(1/s^n\)
\(e^{-a t}\) \(\dfrac{1}{s + a}\)
\(t e^{-a t}\) \(\dfrac{1}{(s+a)^2}\)
\(\dfrac{1}{(n-1)!} t^{n-1} e^{-a t}\) \(\dfrac{1}{(s+a)^n}\)
\(\dfrac{1}{a-b}(e^{a t} - e^{b t})\) \(\dfrac{1}{(s-a)(s-b)}\) (\(a\ne b\))
\(\dfrac{1}{a-b}(a e^{a t} - b e^{b t})\) \(\dfrac{s}{(s-a)(s-b)}\) (\(a\ne b\))
\(\sin \omega t\) \(\dfrac{\omega}{s^2 + \omega^2}\)
\(\cos \omega t\) \(\dfrac{s}{s^2 + \omega^2}\)
\(e^{a t} \sin \omega t\) \(\dfrac{\omega}{(s-a)^2 + \omega^2}\)
\(e^{a t} \cos \omega t\) \(\dfrac{s-a}{(s-a)^2 + \omega^2}\)

Online Resources for Section C.3

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