The astronomical theory and data compared - Ice Ages and Interglacials: Measurements, Interpretation, and Models - page 307

Figure 10.21. Spectral distribution of frequencies corresponding to function F ð t Þ¼
cos ð 1 : 5t Þþ cos ð 2 : 5t Þ . Principal frequencies are at 0.23 and 0.42 units.
Figure 10.22. A hypothetical function with quasi-periodic behavior.
10.3.2 Spectral analysis of solar and paleoclimate data
M&M described a number of alternative approaches for estimating the
spectral distributions corresponding to solar and paleoclimate data. These are
beyond the scope of this topic and we refer the reader to M&M for information
on these methods. We will content ourselves here with merely commenting on
their results.