收益率的分解 无风险利率

近似形式：

名义无风险利率 = 实际无风险利率 + 预期的通货膨胀
nominal risk-free rate = real risk-free rate + expected inflation rate

精确形式：
(1 + nominal risk-free rate) = (1 + real risk-free rate) x (1+ expected inflation rate)