public static double KL(double[] fs, double[] fs2) {
		double klScore = 0.0D, phi_i1, phi_i2;
		klScore = 0.0;
		for (int v = 0; v < fs.length; v++) {
			// cal KL Div by summing
			phi_i1 = fs[v];
			phi_i2 = fs2[v];
			if (phi_i1 > 0 && phi_i2 > 0)
				klScore += phi_i1 * Math.log(phi_i1 / phi_i2);
		}
		return klScore;
	}