Signals and systems/GF Fourier

The Fourier series is used to analyze arbitrary periodic functions by showing them as a composite of sines and cosines. A function is considered periodic if $x(t)=x(t+T)\,$ for $T\neq 0$. The exponential form of the Fourier series is defined as $x(t)=\sum _{n=-\infty }^{\infty }\alpha _{n}e^{{j2\pi nt}/T}\,$

Notes

$e^{j\theta }=cos\theta +jsin\theta \,$