maarten00

/**
 * Copy of Excel's PMT function.
 * Credit: http://stackoverflow.com/questions/2094967/excel-pmt-function-in-js
 *
 * @param rate_per_period       The interest rate for the loan.
 * @param number_of_payments    The total number of payments for the loan in months.
 * @param present_value         The present value, or the total amount that a series of future payments is worth now;
 *                              Also known as the principal.
 * @param future_value          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 0 (zero), that is, the future value of a loan is 0.