= Zero-coupon yield to maturity
{title2=$R(t,T)=-\log P(t,T)/(T-t)$}
The continuously compounded yield of a unit-face <zero-coupon bond> is the constant rate producing its current discount factor over the remaining maturity. It equals the maturity average of the <instantaneous forward rate>. Differentiation gives $f(t,T)=R(t,T)+(T-t)R_T(t,T)$, and both rates tend to the <short rate> as $T\downarrow t$. This definition uses continuous compounding; quoted coupon-bond yields require a different cash-flow equation.
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