Fourier series :

Fourier series is able to represent any precewise regular function in the range [0,2L]

• Dirichlet conditions:f(x) has only a finite number of discontinuities and only a finite number of extreme values(maximum and minimum).
• Functions satifying these conditions may be called piecewise regular.

Square wave

for n_max=15

Full wave rectifier :

for n_max=14

Sawtooth wave :

for n_max=15