Demonstrations
Rotating phasors
\(z(t)=Ae^{i(\omega t+\phi)}\)
- Euler’s formula
- complex exponentials
- phasors
Two-dimensional sinusoid
\(\operatorname{Re}\{Ae^{i\phi}e^{ikx}e^{i\ell y}\}\)
- spatial frequency
- wave vector
- 2D Fourier transform
Maxwell plane wave
\(\operatorname{Re}\{E(x,t)\}=E_0\cos(\omega t-kx)\)
- plane waves
- electromagnetism
- wave propagation
2D FFT image compression
Python + NumPy + WebAssembly
- image compression
- sparse spectral representations
- 2D FFT
Cepheid variable star
Programming task 1 · Fourier series
- Fourier series
- periodic signals
- spectrum
Zebrapard phase swap
\(\mathcal{F}^{-1}\{|I_1|e^{i\angle I_2}\}\)
- magnitude and phase
- image reconstruction
- 2D FFT
Dirac comb
\(x_N(t)=T^{-1}\sum_{k=-N}^{N}e^{i2\pi kt/T}\)
- impulse train
- Fourier series
- sampling
Audio FFT compression
Listen to sparse Fourier reconstruction
- audio compression
- sparse spectral representations
- FFT
Gibbs phenomenon
\(x_N(t)=\frac12+\frac{2}{\pi}\sum_{m=0}^{N-1}\frac{\sin((2m+1)2\pi t/T)}{2m+1}\)
- Fourier series
- Heaviside step
- overshoot
Waterfall spectral analyzer
\(\left|\operatorname{STFT}\{x(t)\}\right|\)
- waterfall spectrum
- STFT
- time-frequency analysis