https://github.com/cran/fields
Tip revision: 8eab500c3dad2103092ff68706417414fe53e16b authored by Doug Nychka on 22 September 2009, 20:23:49 UTC
version 6.01
version 6.01
Tip revision: 8eab500
periodic.cov.1d.R
# 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.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)
}