https://github.com/cran/fields
Tip revision: 04279c16ce718b82025aae97f6fcd30ba3a8b1c5 authored by Doug Nychka on 05 September 2011, 20:18:33 UTC
version 6.6
version 6.6
Tip revision: 04279c1
periodic.cov.1d.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
"periodic.cov.1d" <- function(x1, x2, a, b) {
pairdist <- rdist(x1, x2)%%(b - a)/(b - a)
bernoulli4 <- pairdist^4 - 2 * (pairdist^3) + pairdist^2 -
1/30
cov <- ((-1) * bernoulli4)/(4 * 3 * 2)
cov <- cov + (max(cov) - min(cov))/4
cov <- cov/max(abs(cov))
return(cov)
}