# Additional material

## 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

## Wave Equation

Here are different animations of vibrating strings.

#### Normal modes

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