angle is a MATLAB® function.
Generate a signal that consists of two sinusoids of frequencies 15 Hz and 40 Hz. The signal is sampled at 100 Hz for one second.
fs = 100; t = 0:1/fs:1-1/fs; x = sin(2*pi*15*t) + sin(2*pi*40*t);
Compute the discrete Fourier transform of the signal. Find the phase of the transform and plot it as a function of frequency.
y = fft(x); phs = unwrap(angle(y)); ly = length(y); f = (0:ly-1)/ly*fs; plot(f,phs/pi) xlabel 'Frequency (Hz)' ylabel 'Phase / \pi' grid