The Dagum family of isotropic correlation functions
SteamAdm
A function $ ho:[0,infty) o(0,1]$ is a completely monotonic function if and only if $ ho(Vertmathbf{x}Vert^2)$ is positive definite on $mathbb{R}^d$ for all $d$ and
A function $ ho:[0,infty) o(0,1]$ is a completely monotonic function if and only if $ ho(Vertmathbf{x}Vert^2)$ is positive definite on $mathbb{R}^d$ for all $d$ and