[Math] What kind of curve is made of half circles

Question

I have this curve. It's definitely no sine or cosine. It consists of half circles. How do you call it and how do you describe it mathematically?

Answer 1

Bruteforced answer (don't take this too seriously)

\begin{equation} y=\sqrt{1-(x-2n)^2}, \qquad n\in\mathbb{Z} \\ y \ge 0 \quad \text{if} \quad n|2 \\ y \le 0 \quad \text{if} \quad n\not|\ 2 \end{equation}

Replace $1$ with $r^2$ if you want the semi-circles of arbitrary radius.