Function Yield within with keys returns the theoretical bond yield(s) to maturity (same as internal rate of return) of the referenced bond(s) as of a given reference date Tˢ
Here the yield is defined as the single rate r that when used to discount all future bond cash flows down to time Tˢ, the resulting present value equals a given dirty bond price at the same time Tˢ
There exist 2 distinct methods for obtaining the yield:
1) From a given as of time Tˢ, which is used to imply the needed respective dirty price.
2) From a given discounting yield curve that is used to calculate the needed dirty price at time Tˢ
If the settlement date Tˢ is not explicitly given, it will be set to the bond's settlement date as implied by a trade transaction assumed to occur on the T₀ (typically today).
PRECAUTION: This function treats the referenced bond as if it were a fixed rate bond even if this is not the case!
All index-linked cash flows are treated as fixed cash flows that pay the amount forecasted by the corresponding curve.