A =
Matrix([0.678, 0.108, -0.199, -0.556]
       [0.108, -0.825, 0.494, -0.769]
       [-0.199, 0.494, -0.467, -0.55]
       [-0.556, -0.769, -0.55, -0.41])

λ =
[-1.4464022721723646, -1.0646892019678795, 0.4339243198221241, 1.0531671543181205]

v^T =
[-0.12616702117616707, -0.7643833949513157, 0.004844626922265541, -0.6322787659570878]
[0.2472443226187, -0.3829314686707851, 0.784955378138012, 0.4196174323912988]
[-0.5766511390888165, 0.4159903773478487, 0.589482999093223, -0.38332135802955664]
[-0.768391561307074, -0.3098927585122487, -0.19060791615841557, 0.5265068936220042]



Test of implementation:

A*v_1 - λ_1*v_1 =
Matrix([-2.498001805406602e-16]
       [2.220446049250313e-16]
       [-1.1188966420050406e-16]
       [1.1102230246251565e-16])

A*v_2 - λ_2*v_2 =
Matrix([-5.551115123125783e-17]
       [1.1102230246251565e-16]
       [0.0]
       [0.0])

A*v_3 - λ_3*v_3 =
Matrix([-1.1102230246251565e-16]
       [-1.6653345369377348e-16]
       [1.6653345369377348e-16]
       [1.6653345369377348e-16])

A*v_4 - λ_4*v_4 =
Matrix([-1.1102230246251565e-16]
       [5.551115123125783e-17]
       [2.7755575615628914e-17]
       [-2.220446049250313e-16])