exp.earth.cov.r
# fields, Tools for spatial data
# Copyright 2004-2011, Institute for Mathematics Applied Geosciences
# University Corporation for Atmospheric Research
# Licensed under the GPL -- www.gpl.org/licenses/gpl.html
"Exp.earth.cov" <- function(x1, x2, theta = 1) {
exp(-rdist.earth(x1, x2)/theta)
}