Fig. 7.

The slow flow on S near the top fold $F_3$. Vectors of the slow flow on S are shown together with the orbit segment from Figure 5c. The direction of flow on S is indicated by the arrows where hotter colours correspond to vectors with larger magnitudes. The folded focus is the black dot on $F_3$ with the uniformly repelling and attracting parts of $F_3$coloured light and dark green, respectively. Panels (a) and (b) show the process from two opposite viewpoints, and panels (c) and (d) show corresponding close-up views near $F_3$.