text: #ifndef TOOLS_H_
  #define TOOLS_H_
  #include <vector>
  #include "Eigen/Dense"
  
  using Eigen::MatrixXd;
  using Eigen::VectorXd;
  using namespace std;
  
  class Tools {
  public:
    /**
    * Constructor.
    */
    Tools();
  
    /**
    * Destructor.
    */
    virtual ~Tools();
  
    /**
    * A helper method to calculate RMSE.
    */
    VectorXd CalculateRMSE(const vector<VectorXd> &estimations, const vector<VectorXd> &ground_truth);
  
    /**
    * A helper method to calculate Jacobians.
    */
    MatrixXd CalculateJacobian(const VectorXd& x_state);
  
  };
  
  #endif /* TOOLS_H_ */