PRINC_PAYMENT Function
Evaluates the payment on the principal for a specified period.
Usage
result = PRINC_PAYMENT(rate, period, n_periods, present_value, future_value, when)
Input Parameters
rate—Interest rate.
period—Payment period.
n_periods—Total number of periods.
present_value—The current value of a stream of future payments, after discounting the payments using some interest rate.
future_value—The value, at some time in the future, of a current amount and a stream of payments.
when—Time in each period when the payment is made, either 0 for at the end of period or 1 for at the beginning of period.
Returned Value
result—The payment on the principal for a given period. If no result can be computed, NaN is returned.
Input Keywords
Double—If present and nonzero, double precision is used.
Discussion
Function PRINC_PAYMENT computes the payment on the principal for a given period. It is computed using the following:
where paymenti is computed from the function PAYMENT for the ith period and interesti is calculated from the function INT_PAYMENT for the ith period.
Example
In this example, PRINC_PAYMENT computes the principal paid for the first year on a 30-year $100,000 loan with an annual interest rate of 8%. The payment is made at the end of each year.
PRINT, PRINC_PAYMENT(0.08, 1, 30, 100000., 0., 0)
; PV-WAVE prints: -882.742
