code: def funTransSectX(theta, rho):
      
      return np.matrix([[np.cos(theta), rho * np.sin(theta)], [-np.sin(theta) / rho, np.cos(theta)]], dtype=np.double)
docs: Sector matrix in X
  
      :param theta: bend angle, in [rad]
      :param rho: bend radius, in [m]
      :return: 2x2 numpy array