Orthonormal coframe in Painlevé–Gullstrand coordinates
= Orthonormal coframe in Painlevé–Gullstrand coordinates
An orthonormal coframe is
$$
e^0=dt,
\qquad e^1=dr+\sqrt{\frac{2M}{r}}\,dt,
\qquad e^2=r\,d\theta,
\qquad e^3=r\sin\theta\,d\phi.
$$
= Orthonormal coframe in Painlevé–Gullstrand coordinates
An orthonormal coframe is
$$
e^0=dt,
\qquad e^1=dr+\sqrt{\frac{2M}{r}}\,dt,
\qquad e^2=r\,d\theta,
\qquad e^3=r\sin\theta\,d\phi.
$$