# 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
"Rad.simple.cov" <- function(x1, x2, p = 1, with.log = TRUE, 
    with.constant = TRUE, C = NA, marginal = FALSE) {
    if (marginal) {
        return(rep(1, nrow(x1)))
    }
    if (!is.matrix(x1)) 
        x1 <- as.matrix(x1)
    if (!is.matrix(x2)) 
        x2 <- as.matrix(x2)
    d <- ncol(x1)
    n1 <- nrow(x1)
    n2 <- nrow(x2)
    m <- (d + p)/2
    temp <- rdist(x1, x2)
    if (with.constant) {
        Amd <- radbas.constant(m, d)
    }
    else {
        Amd <- 1
    }
    if ((d%%2 == 0) & (with.log)) {
        temp <- Amd * ifelse(temp < 1e-10, 0, temp^(p/2) * log(temp))
    }
    else {
        temp <- Amd * temp^(p)
    }
    #
    #
    if (is.na(C[1])) {
        return(temp)
    }
    else {
        return(temp %*% C)
    }
}