特征值分解
(x^2 - x - 1 = 0)
移项,除以x,求x的非零解
(x = 1 + frac{1}{x}, x = 1 + frac{1}{1 + frac{1}{1 + ...}})
迭代
(x_{n + 1} = 1 + frac{1}{x_n}) (x_0 = 1)