text: #ifndef __DOUBLE_PENDULUM_H_
  #define __DOUBLE_PENDULUM_H_
  
  #include <SFML/Graphics.hpp>
  #include <armadillo>
  
  
  class DoublePendulum {
  
      private:
  
          // Representation of the pendulums
          sf::RectangleShape pend1;
          sf::RectangleShape pend2;
  
          // Representation of the pivots
          sf::CircleShape pivot1;
          sf::CircleShape pivot2;
  
          double gravity;
  
          // Pivot vector coordinates
          arma::vec P1;
          arma::vec P2;
  
          // Center of mass vector coordinates
          arma::vec X1;
          arma::vec X2;
  
          // Vector from pivot to center of mass
          arma::vec R1;
          arma::vec R2;
          // Respective lengths
          double R1Length;
          double R2Length;
  
          // Angle at pivot between R and the downward vertical position [rad]
          double theta1;
          double theta2;
  
          // Vector from pivot 1 to pivot 2
          arma::vec L1;
          // Respective length
          double L1Length;
  
          // Angle from R1 to L1 [rad]
          double phi;
  
          // Mass of the pendulums [kg]
          double m1;
          double m2;
  
          // Rotation interia about the center of mass of the pendulums
          double I1;
          double I2;
  
  
      public:
  
          // Default constructor
          DoublePendulum();
  
          // Draw figures
          void draw(sf::RenderWindow *window);
  
  };
  
  #endif // __DOUBLE_PENDULUM_H_
  