Linearized point-mass metric in radial Cartesian form (source code)

= Linearized point-mass metric in radial Cartesian form

For a point mass and $r>0$, write
$$
h_{00}=\frac{2GM}{r},
\qquad
h_{ij}=f(r)x_i x_j.
$$
The vacuum scalar-curvature equation gives $rf'+3f=0$, so $f=C/r^3$. The remaining vacuum equations fix $C=2GM$ in the corresponding Schwarzschild gauge.