CUM_INTR Function

Evaluates the cumulative interest paid between two periods.

Usage

result = CUM_INTR (rate, n_periods, present_value, start, end_per, when)

Input Parameters

rate—Interest rate.

n_periods—Total number of payment periods. n_periods cannot be less than or equal to 0.

present_value—The current value of a stream of future payments, after discounting the payments using some interest rate.

start—Starting period in the calculation. start cannot be less than 1; or greater than end_per.

end_per—Ending period in the calculation.

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 cumulative interest paid between the first period and the last period. If no result can be computed, NaN is returned.

Input Keywords

Double—If present and nonzero, double precision is used.

Discussion

Function CUM_INTR evaluates the cumulative interest paid between the first period and the last period.

It is computed using the following:

 

where interest_i is computed from the function INT_PAYMENT for the i^th period.

Example

In this example, CUM_INTR computes the total interest paid for the first year of a 30-year $200,000 loan with an annual interest rate of 7.25%. The payment is made at the end of each month.

PRINT, CUM_INTR(0.0725 / 12, 12*30, 200000., 1, 12, 0)

; PV-WAVE prints: -14436.5