rktnb <- function(n, size, k, mu, xpred = 1) {
if (length(n) > 1)
n <- length(n)
stopifnot(n == as.integer(n))
stopifnot(n > 0)
stopifnot(is.numeric(xpred))
stopifnot(length(xpred) > 0)
stopifnot(all(xpred == as.integer(xpred)))
stopifnot(is.numeric(mu))
stopifnot(length(mu) > 0)
stopifnot(all(mu > 0))
stopifnot(is.numeric(k))
stopifnot(length(k) >= 0)
stopifnot(all(k == as.integer(k)))
stopifnot(is.numeric(size))
stopifnot(length(size) >= 0)
stopifnot(all(size > 0))
.C("aster_rktnb",
n = as.integer(n),
lenxp = length(xpred),
lenmu = length(mu),
lenk = length(k),
lenalpha = length(size),
xpred = as.double(xpred),
mu = as.double(mu),
k = as.integer(k),
alpha = as.double(size),
result = double(n), PACKAGE = "aster")$result
}