def METHOD_NAME(self):
    self.add_input('x', np.ones(2))
    self.add_output('y', np.ones(2))
    self.mtx = np.array([
        [3., 4.],
        [2., 3.],
    ])
    # Inverse is
    # [ 3.,-4.],
    # [-2., 3.],
    #self.declare_partials('y', 'x', val=-np.eye(2))
    #self.declare_partials('y', 'y', val=self.mtx)
    self.declare_partials('*', '*')