2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/76835We solve the functional equations $$ \begin{vmatrix} 1 & 1 & 1 f(x) & f(y) & f(z) f\sp{\prime}(x)& f\sp{\prime}(y)& f\sp{\prime}(z) \end{vmatrix} =0,\quad\quad \begin{vmatrix} 1 & 1 & 1 f(x) & g(y) & h(z) \\ f\sp{\prime}(x)& g\sp{\prime}(y)& h\sp{\prime}(z) \end{vmatrix} =0, for suitable functions $f$, $g$ and $h$ subject to $x+y+z=0$. These equations essentially characterise the Weierstrass $\wp$-function and its degenerations. %\quad\quad x+y+z=0. $$11 pages LaTex2eClassical Analysis and ODEsMathematical PhysicsExactly Solvable and Integrable Systems39B22, 30D05, 33E05text