Returns the interest payment for a given period for an investment based on periodic, constant payments and a constant interest rate.
The interest rate per period.
The period for which you want to find the interest and must be in the range 1 to nper.
The total number of payment periods in an annuity.
The present value, or the lump-sum amount that a series of future payments is worth right now.
The future value, or a cash balance you want to attain after the last payment is made. If fv is omitted, it is assumed to be BLANK.
The number 0 or 1 and indicates when payments are due. If type is omitted, it is assumed to be 0.
Contributors: Alberto Ferrari, Marco Russo