YTM - the IRR of a bond investment. If the underlying bond is annual, it is annual; if the underlying bond is semi-annual, it is semi-annual.
EAY - 顾名思义, 有效年化利率. for a annual bond, EAY=YTM; for a semi-annual bond 1+EAY=(1+YTM/2)^2
BEY - 一种利率的表达形式而已 BEY 就是半年一次Coupon的Bond 的YTM. 可以将任何利率转化为此形式方便与已有的bond YTM做比较, 计算第一步: 求的任何利率的EAY 第二步 for a semi annual bond, BEY=((1+EAY)^0.5-1)x2; for an annual bond, BEY=EAY.
