# Division by 2 is made to have full period from 0 to 2pi
def src_f(x):
  return 4*np.sin(x/2)**3*np.cos(x/2)

# Example, fs being sampling frequency and f_c the fundemental of the waveform
src_d[0:fs/f_c] = src_f(w)[0:fs/f_c]