# Program to identify the freqs amps and phases of a function # that is a sum of sines each of which oscillates an integral number # of times for N points N = 1024 # FFT works best with powers of 2 t = seq(from=0,by=2*pi/N,length=N) # N evenly spaced pts 0 -- 2*pi f = 100 # number of cycles per N pts y = 1*cos(f*t+1) + 2*cos(2*f*t + 2) + 3*cos(3*f*t +3); plot(y[1:100],type="l") Y = fft(y) # take the fft plot(Mod(Y[1:(N/2)]) / (N/2)) # plot of Modulus = amplitudes #plot(Y[1:(N/2)])