Riemannian index form (source code)

= Riemannian index form
{c}
{title2=$I(V,W)$}
{wiki=Jacobi_field#Index_form}

Along a geodesic $\gamma$ with tangent $T$, the index form on endpoint-vanishing vector fields is
$$
I(V,W)=\int\bigl(\langle D_tV,D_tW\rangle-\langle R(V,T)T,W\rangle\bigr)dt.
$$