Joseph-Louis Lagrange

1. Lagrange Multipliers

Method for finding local maxima/minima subject to constraints.

$$ \nabla f = \lambda \nabla g $$

2. Lagrangian Mechanics

A reformulation of classical mechanics.

$$ \frac{d}{dt} \left( \frac{\partial L}{\partial \dot{q}_i} \right) - \frac{\partial L}{\partial q_i} = 0 $$