code: def stSpectralFlux(X, X_prev):
      
      # compute the spectral flux as the sum of square distances:
      sumX = numpy.sum(X + eps)
      sumPrevX = numpy.sum(X_prev + eps)
      F = numpy.sum((X / sumX - X_prev/sumPrevX) ** 2)
  
      return F
docs: Computes the spectral flux feature of the current frame
      ARGUMENTS:
          X:            the abs(fft) of the current frame
          X_prev:        the abs(fft) of the previous frame