# Euler-Lagrange equation

This is a necessary condition for $LaTeX: y$ to solve the classical problem in variational calculus:
$LaTeX: \mbox{div}(F_{\zeta} (x, y(x), \nabla y(x))) = F_{\lambda}(x, y(x), \nabla y(x))$,
where $LaTeX: F(x, \lambda, \zeta): \Omega \times \mathbb{R} \times \mathbb{R}^n \rightarrow \mathbb{R}$.