Top: the full line shows the singular spectrum and the dashed line shows an average of 100 runs of Monte Carlo simulation. 2nd row: smoothed time series (same as Fig. 1 – bottom). 3rd row: reconstructed time series using only the leading 4 eigenvalues, showing a strong beating effect. Bottom: Fourier transform of the reconstructed series. Note that the frequencies around 2.4 cd^-1 are by far the dominant ones.