Videos from Math 4D
Morten Nome, the lecturer for Math 4D (almost the same as Math 4N), made some interesting videos.
Fourier series approximation
Fourier series approximation of the sawtooth wave Fourier approximation
Here are different animations of vibrating strings.
Fundamental mode Fundamental mode Second mode Second mode Third mode Third mode Fourth mode Fourth mode
Initial conditions (no initial velocity)
Quadratic function Quadratic function Triangular wave Triangular wave