Chapter 9: Special Functions

interest_payment

Evaluates the interest payment for an investment for a given period.

Synopsis

#include <imsl.h>

float imsl_f_interest_payment (float rate, int period, int n_periods, float present_value, float future_value, int when)

The type double function is imsl_d_interest_payment.

Required Arguments

float rate   (Input)
Interest rate.

int period   (Input)
Payment period.

int n_periods   (Input)
Total number of periods.

float present_value   (Input)
The current value of a stream of future payments, after discounting the payments using some interest rate.

float future_value   (Input)
The value, at some time in the future, of a current amount and a stream of payments.

int when   (Input)
Time in each period when the payment is made, either IMSL_AT_END_OF_PERIOD or IMSL_AT_BEGINNING_OF_PERIOD. For a more detailed discussion on  see the Usage Notes section of this chapter.

Return Value

The interest payment for an investment for a given period.  If no result can be computed, NaN is returned.

Description

Function imsl_f_interest_payment computes the interest payment for an investment for a given period.

It is computed using the following:

Example

In this example, imsl_f_interest_payment computes the interest payment for the second year of a 25-year $100,000 loan with an annual interest rate of 8%.  The payment is made at the end of each period.

 

#include <stdio.h>

#include "imsl.h"

 

void main()

{

  float rate = .08;

  int period = 2;

  int n_periods = 25;

  float present_value = 100000.00;

  float future_value = 0.0;

  int when = IMSL_AT_END_OF_PERIOD;

  float interest_payment;

 

  interest_payment = imsl_f_interest_payment (rate, period, n_periods,

                                       present_value, future_value, when);

  printf ("The interest due the second year on the $100,000 ");

  printf ("loan is $%.2f.\n", interest_payment);

}

Output

The interest due the second year on the $100,000 loan is $-7890.57.


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