docs: public static double Bhattacharyya(double[] histogram1, double[] histogram2) {
          int bins = histogram1.length; // histogram bins
          double b = 0; // Bhattacharyya's coefficient
  
          for (int i = 0; i < bins; i++)
              b += Math.sqrt(histogram1[i]) * Math.sqrt(histogram2[i]);
  
          // Bhattacharyya distance between the two distributions
          return Math.sqrt(1.0 - b);
      }