Обратная матрица

def reverse(a):
    l, u = decomposition_lu(a)
    n = a.shape[0]
    reversed_matrix = np.matrix(np.zeros([n, n]))

    for i in range(n):
        ans = np.matrix(np.zeros([n, 1]))
        ans[i] = 1
        x = solve_lu(l, u, ans)

        for j in range(n):
            reversed_matrix[j, i] = x[j]

    return reversed_matrix