code: public static double Canberra(double x1, double y1, double x2, double y2) {
          double distance;
  
          distance = Math.abs(x1 - x2) / (Math.abs(x1) + Math.abs(x2));
          distance += Math.abs(y1 - y2) / (Math.abs(y1) + Math.abs(y2));
  
          return distance;
      }
docs: Gets the Canberra distance between two points.
  
  @param x1 X1 axis coordinate.
  @param y1 Y1 axis coordinate.
  @param x2 X2 axis coordinate.
  @param y2 Y2 axis coordinate.
  @return The Canberra distance between x and y.