kron.R
##
## k r o n . R Kronecker product
##
kron <- function(a, b) {
if (length(a) == 0 || length(b) == 0) return(c())
if (!(is.numeric(a) || is.complex(a)) ||
!(is.numeric(b) || is.complex(b)))
stop("Arguments 'a' and 'b' must be real/complex vectors/matrices.")
kronecker(a, b)
}