The Dagum family of isotropic correlation functions

Christian Berg, Jorge Mateu, Emilio Porcu

A function $\rho :[0,\infty )\to (0,1]$ is a completely monotonic function if and only if $\rho (\Vert \mathbf{x}{\Vert }^2)$ is positive definite on ${\mathbb{R}}^d$ for all $d$ and thus it repre…