Laplace Transform Properties#
No. |
Name |
Time Domain \(f(t)\) |
Complex Frequency Domain \(F(s)\) |
---|---|---|---|
1. |
Linearity |
\(a_1f_1(t)+a_2f_2(t)+\cdots+a_nf_n(t)\) |
\(a_1F_1(s)+a_2F_2(s)+\cdots+a_nF_n(s)\) |
2. |
Time shifting |
\(\displaystyle{f(t-a)}u_0(t-a)\) |
\(\displaystyle{e^{-a s}F(s)}\) |
3. |
Frequency shifting |
\(\displaystyle{e^{-as}f(t)}\) |
\(\displaystyle{F(s+a)}\) |
4. |
Time scaling |
\(f(a t)\) |
\(\displaystyle{\frac{1}{a}F\left(\frac{s}{a}\right)}\) |
5. |
Time differentiation |
\(\displaystyle{\frac{d}{dt}\,f(t)}\) |
\(\displaystyle{sF(s)-f(0^-)}\) |
6. |
Frequency differentiation |
\(\displaystyle{tf(t)}\) |
\(\displaystyle{-\frac{d}{ds}F(s)}\) |
7. |
Time integration |
\(\displaystyle{\int_{-\infty}^{t}f(\tau)d\tau}\) |
\(\displaystyle{\frac{F(s)}{s}+ \frac{f(0^-)}{s}}\) |
8. |
Frequency integration |
\(\displaystyle{\frac{f(t)}{t}}\) |
\(\displaystyle{\int_s^\infty F(\sigma)\,d\sigma}\) |
9. |
Time Periodicity |
\(\displaystyle{f(t + nT)}\) |
\(\displaystyle{\frac{\int_0^T f(t)e^{-st}\,dt}{1 - e^{-sT}}}\) |
10. |
Initial value theorem |
\(\displaystyle{\lim_{t\rightarrow 0} f(t)}\) |
\(\displaystyle{\lim_{s\rightarrow \infty}sF(s) = f(0^-)}\) |
11. |
Final value theorem |
\(\displaystyle{\lim_{t\rightarrow \infty} f(t)}\) |
\(\displaystyle{\lim_{s\rightarrow 0}sF(s) = f(\infty)}\) |
12. |
Time convolution |
\(\displaystyle{f_1(t)*f_2(t)}\) |
\(\displaystyle{F_1(js) F_2(s)}\) |
13. |
Frequency convolution |
\(\displaystyle{f_1(t)f_2(t)}\) |
\(\displaystyle{\frac{1}{j2\pi}F_1(s)*F_2(s)}\) |
See also: Wikibooks: Engineering_Tables/Laplace_Transform_Properties and Laplace Transform—WolframMathworld for more complete references.