In this note we extend our study of the rich geometry of the graph of a curve defined as the weighted sum of two exponentials. Let $\gamma_{ a,b}^{ s}: [0,1] \rightarrow \mathbb{ C}$ be defined as $$\gamma_{ a,b}^s(t) = (1-s) \exp(2 \pi i a t) + (1+s) \exp(2\pi i b t) $$ in which $1\leq a < b$ are two positive integers and $s \in [-1,1]$. In the first part we determined the symmetry groups of the graphs of $\gamma_{ a,b}:=\gamma_{ a,b}^0$. The main aim of this note is to study the continuous transition of the graph of the curve when $s$ changes from $-1$ to $1$. As a main result we determine the winding numbers $\mathrm{ wind}(\gamma_{ a,b}^s,0)$ for $s \in [-1,1] \setminus \{ 0 \}$ as well as the set of cusp points of each such curve. This sheds further light on our initial symmetry result and provides more non-trivial albeit easy-to-state examples of advanced concepts of geometry and topology.
Categories: math.NT math.DG