Beltrami identity
= Beltrami identity
{c}
{wiki}
When a variational integrand $f(z,z')$ has no explicit dependence on the independent variable, every extremal satisfies
$$
f-z'f_{z'}=\text{constant}.
$$
= Beltrami identity
{c}
{wiki}
When a variational integrand $f(z,z')$ has no explicit dependence on the independent variable, every extremal satisfies
$$
f-z'f_{z'}=\text{constant}.
$$