https://github.com/cran/fields
Tip revision: 0e015763c23043fc79b36e20177cde5e8b4eb092 authored by Doug Nychka on 06 July 2010, 19:17:12 UTC
version 6.3
version 6.3
Tip revision: 0e01576
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)
}