According to the correspondence principle, in certain limits the quantum equations of states must approach Hamilton's equations of motion. The latter state the following relation between the generalized coordinate q (e.g. position) and the generalized momentum p : { q ˙ ˙ = ∂ ∂ H ∂ ∂ p = { q , H } ; p ˙ ˙ = − − ∂ ∂ H ∂ ∂ q = { p , H } .