code: private double calcNormalizedDistance(double[] point) {
          double[] center = getCenter();
          double res = 0.0;
  
          for (int i = 0; i < center.length; i++) {
              double diff = center[i] - point[i];
              res += (diff * diff);// variance[i];
          }
          return Math.sqrt(res);
      }
docs: ???????