The Warsaw sine function is the D4364: Real function \begin{equation} (0, 1] \to \mathbb{R}, \quad x \mapsto \sin \left( \frac{1}{x} \right) \end{equation}

The Warsaw sine function is the D4364: Real function \begin{equation} (0, 1] \to \mathbb{R}, \quad x \mapsto \sin ( x^{-1} ) \end{equation}