Computes the first derivative of the Matern correlation function with respect to \(\phi\).
matern.grad.phi(U, phi, kappa)A matrix with the values of the first derivative of the Matern function with respect to \(\phi\) for the given distances.
A vector of distances between pairs of data locations.
The scale parameter \(\phi\).
The smoothness parameter \(\kappa\).
Emanuele Giorgi e.giorgi@lancaster.ac.uk
Claudio Fronterre c.fronterr@lancaster.ac.uk