code: private void normalizeL2(double[] scores) {
  		double square_sum = 0.0;
  		for (int i = 0; i < scores.length; i++) {
  			square_sum += (scores[i] * scores[i]);
  		}
  		double norm = Math.sqrt(square_sum);
  		if (norm != 0)
  			for (int i = 0; i < scores.length; i++) {
  				scores[i] = scores[i] / norm;
  			}
  	}
docs: Returns the L2 norm factor of this vector's values.