Geodesic Hamiltonian (source code)

= Geodesic Hamiltonian
{title2=$H(x,p)=\tfrac12g^{ij}(x)p_ip_j$}

The metric defines this globally smooth <Hamiltonian> on the <cotangent bundle>. With $\omega=dx^i\wedge dp_i$ and $\iota_{X_H}\omega=dH$, its <Hamiltonian vector field> projects to affinely parametrized <geodesics>. The momentum is $p_i=g_{ij}\dot x^j$, and its conserved value is half the squared speed.