Hello,

I don't understand why is amplitude spectrum of Fourier series defined as:

$\displaystyle c_0 = |a_0|$

$\displaystyle c_n = \sqrt{a_n^{2} + b_n^{2}}$

and why is phase spectrum:

$\displaystyle Arg(a_n - b_n)$

Can someone give me an understandable easy explanation.

Thanks.