# Question About the Hamiltonian

1. Oct 6, 2014

### kq6up

If the hamiltonian is defined as $\mathcal{H}\equiv \sum _{ i }^{ all }{ p_{ i }\dot { q } _{ i } } - \mathcal{L}$, how is it considered a function of $p$ and $q$ instead of $p$ and $\dot{q}$?

Chris

2. Oct 6, 2014

### Matterwave

You should make a change of variables at the end to find $\dot{q}$ in terms of $p,q$.