A discrete function $f$ on a discrete surface is just a map $f: V \rightarrow \mathbb{R}$. The derivative of $f$ is the function $df: E \rightarrow \mathbb{R}$ $df(e) = f(\textrm{end}(e))-f(\textrm{start}(e))$. $df$ has the property $df \circ \rho = -df$ One … Continue reading Discrete functions and their derivatives