Interest Rate
Key Interest Rate in Interest Fn refers to the interest rate r that starts accumulating interest according to the conventions defined in key Spec from the reference date d₁ defined in key Accr Start until the date d, where d is the variable input date to the function here.
If more than one reference dates d₁, d₂ , ... , dᵤ are defined in Accr Start, it is possible to associate a different interest rate with each of the dates in d₁, d₂ , ... , dᵤ by entering here a 1D-array array consisting of the v rates r₁, r₂ , ... , rᵥ, establishing the correspondence:
d₁ ↔ r₁ , d₂ ↔ r₂ , ...
It is allowed that v < u in which case the tail reference dates dᵥ₊₁ , ... , dᵤ are all paired with the last rate rᵥ
For example, it is allowed to have several reference dates d₁, d₂ , ... , dᵤ but only one rate r, in which case the rate r applies to all dates in d₁, d₂ , ... , dᵤ
But if two rates r₁ and r₂ are defined, then the rate r₁ applies only to the date d₁, whereas the rate r₂ applies to all remaining dates d₂ , ... , dᵤ
In the case of several interest rates the applicable set of conventions is selected as described at Spec