Calculates the payment for a loan based on constant payments and a constant interest rate.
The interest rate for the loan.
The total number of payments for the loan.
The present value, or the total amount that a series of future payments is worth now; also known as the principal.
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 (zero) or 1 and indicates when payments are due.
Contributors: Alberto Ferrari, Marco Russo