if (is.null(labels)) labels <- as.character(1:N)
ans <- .C("nj", as.double(X), as.integer(N), integer(2*N - 3),
integer(2*N - 3), double(2*N - 3),
if (is.null(labels)) labels <- as.character(1:N)
ans <- .C("nj", as.double(X), as.integer(N), integer(2*N - 3),
integer(2*N - 3), double(2*N - 3),