code: protected static double calculateReachDistance(LofPoint basePoint, LofPoint targetPoint)
      {
          double distance = MathUtils.distance(basePoint.getDataPoint(), targetPoint.getDataPoint());
  
          double reachDistance = (double) ComparatorUtils.max(distance, targetPoint.getkDistance(),
                  ComparatorUtils.NATURAL_COMPARATOR);
          return reachDistance;
      }
docs: basePointのtargetPointに関する到達可能距離(Reachability distance)を算出する。
  
  @param basePoint 算出元対象点
  @param targetPoint 算出先対象点
  @return 到達可能距離