... INTRATE(settlement,maturity,investment,redemption[,basis]) . INTRATE calculates and returns the interest rate of a fully vested security. @settlement is the settlement date of the security. @maturity is the maturity date of the security. @investment is the prize of the security paid at @settlement date and @redemption is the amount to be received at @maturity date. @basis is the type of day counting system you want to use: . 0 US 30/360 . 1 actual days/actual days . 2 actual days/360 . ...