# fields, Tools for spatial data # Copyright 2004-2007, Institute for Mathematics Applied Geosciences # University Corporation for Atmospheric Research # Licensed under the GPL -- www.gpl.org/licenses/gpl.html "periodic.plane.3d" <- function (x1, x2, a = 0, b = 365, theta = 1) { cov.per1d <- periodic.cov.1d(x1[, 1], x2[, 1], a, b) cov.vert <- Exp.cov(x1[, c(2, 3)], x2[, c(2, 3)], theta = theta) cov <- cov.per1d * cov.vert return(cov) }