# 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
"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
}