code: def hessian(self, x, y, Rs, theta_Rs, r_core, center_x=0, center_y=0):
  
          
  
          if Rs < 0.0001:
              Rs = 0.0001
          x_ = x - center_x
          y_ = y - center_y
          R = np.sqrt(x_ ** 2 + y_ ** 2)
  
          rho0 = self._alpha2rho0(theta_Rs=theta_Rs, Rs=Rs, r_core=r_core)
  
          kappa = self.density_2d(x_, y_, Rs, rho0, r_core)
  
          gamma1, gamma2 = self.cBurkGamma(R, Rs, rho0, r_core, x_, y_)
          f_xx = kappa + gamma1
          f_yy = kappa - gamma1
          f_xy = gamma2
          return f_xx, f_yy, f_xy
docs: :param x: x coordinate
          :param y: y coordinate
          :param Rs: scale radius
          :param rho0: central core density
          :param r_core: core radius
          :param center_x:
          :param center_y:
          :return: