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
radbas.constant.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
"radbas.constant" <- function(m, d) {
# local gamma function to avoid imprecision warnings for negative arguments.
gamma.local <- function(x) {
if (x < 0) {
temp <- 1
while (x < 0) {
temp <- temp * x
x <- x + 1
}
return(gamma(x)/temp)
}
else {
gamma(x)
}
}
if (d%%2 == 0) {
Amd <- (((-1)^(1 + m + d/2)) * (2^(1 - 2 * m)) * (pi^(-d/2)))/(gamma(m) *
gamma.local(m - d/2 + 1))
}
else {
Amd <- (gamma.local(d/2 - m) * (2^(-2 * m)) * (pi^(-d/2)))/gamma(m)
}
Amd
}