a) Sawtooth function based on timing residuals observed by Gregory et al. (1999). b) Sawtooth function based on the loss of synchronization of the sine functions f(P₁) and f(P₂) of Fig. 3c. c) Sine waves with periods P₁ (black line) and P₂ (red line) starting with synchronized peaks at t = 0. d) Sum of the sine waves. The first five bars are at a regular interval equal to P_average, then the next bar follows at a distance of only 13.25 d (P₁/2), followed by four bars again at a regular interval equal to P_average as before. The two central bars are symmetric with respect to a peak of f(P₂) (Fig. 3c) that is nearly equidistant from the preceeding peak and the delayed peak of f(P₁) (see Appendix).