Most often in Lagrangian mechanics, the Lagrangian L (q, d q / dt, t) is in configuration space, where q = (q 1, q 2,..., q n) is an n - tuple of the generalized coordinates. The Euler–Lagrange equations of motion are d d t ∂ ∂ L ∂ ∂ q ˙ ˙ i = ∂ ∂ L ∂ ∂ q i , q ˙ ˙ i ≡ ≡ d q i d t .