private void caluateD(long[] nk) {
		long sum = nk[0] + 2 * nk[1];
		double Y = 0;
		if (sum > 0)
			Y = nk[0] * 1.0 / sum;
		for (int i = 0; i < K_LIMT; i++) {
			if (nk[i] > 0)
				D[i] = (i + 1) - (i + 2) * Y * nk[i + 1] / nk[i];
		}
	}