code: def rotation_coefs(self):
          
          return [np.cos(self.bearing_rads),
                  np.sin(self.bearing_rads),
                  -1.0*np.sin(self.bearing_rads),
                  np.cos(self.bearing_rads)]
docs: get the rotation coefficents in radians
  
          Returns
          -------
          rotation_coefs : list
              the rotation coefficients implied by Vario2d.bearing