https://github.com/cran/fields
Tip revision: 6769ffc81115fbf0bf7d9c566cf7ac81be0049dc authored by Doug Nychka on 25 July 2005, 00:00:00 UTC
version 3.04
version 3.04
Tip revision: 6769ffc
poisson.cov.r
"poisson.cov" <-
function (x1, x2, eta = 0.2)
{
if (missing(x2))
x2 <- x1
#
# dot products of direction cosines
#
PP1 <- cbind(cos((x1[, 2] * pi)/180) * cos((x1[, 1] *
pi)/180), cos((x1[, 2] * pi)/180) * sin((x1[, 1] *
pi)/180), sin((x1[, 2] * pi)/180))
PP2 <- cbind(cos((x2[, 2] * pi)/180) * cos((x2[, 1] *
pi)/180), cos((x2[, 2] * pi)/180) * sin((x2[, 1] *
pi)/180), sin((x2[, 2] * pi)/180))
D <- (PP1 %*% t(PP2))
con <- (1 - eta^2)^(1.5)
con/(1 - 2 * eta * D + eta^2)^(1.5)
}