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
\(x_{n + 1} = 1 + \frac{1}{x_n}\) \(x_0 = 1\)
