Fourier series approximation

For a continuous-time, T-periodic signal x(t), the N-harmonic Fourier series approximation can be written as

x(t) = a0	+ a1 cos (wot + q1) + a2 cos (2wot + q2)
	+ ... + aN cos (nwot + qN)

where the fundamental frequency w_o is 2 pi / T, the amplitude coefficients a₁, ..., a_N are >= 0, and the radian phase angles satisfy 0 <= q₁, ..., q_N <= 2 pi. To explore the Fourier series approximation, select a labeled signal, use the mouse to sketch one period of a signal, or use the mouse to modify a selected signal. Specify the number of harmonics, N, and click "Calculate." The approximation will be shown in red. In addition, the magnitude spectrum (a plot of a_n vs. n) and phase spectrum (a plot of q_n vs. n)