Evaluates the number of periods for an investment for which periodic and constant payments are made and the interest rate is constant.
Synopsis
#include <imsl.h>
float
imsl_f_number_of_periods (float rate, float payment,
float present_value, float future_value, int when)
The type double function is imsl_d_number_of_periods.
Required Arguments
float rate
(Input)
Interest rate on the investment.
float payment
(Input)
Payment made on the investment.
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 when see the
Usage Notes
section of this chapter.
Return Value
The number of periods for an investment.
Description
Function imsl_f_number_of_periods computes the number of periods for an investment based on periodic, constant payment and a constant interest rate.
It can be found by solving the following:
If rate = 0
If rate ¹ 0
Example
In this example, imsl_f_number_of_periods computes the number of periods needed to pay off a $20,000 loan with a monthly payment of $350 and an annual interest rate of 7.25%. The payment is made at the beginning of each period.
#include <stdio.h>
#include "imsl.h"
void main()
{
float rate = 0.0725 / 12;
float payment = -350.;
float present_value = 20000;
float future_value = 0.;
int when = IMSL_AT_BEGINNING_OF_PERIOD;
float number_of_periods;
number_of_periods = imsl_f_number_of_periods (rate, payment,
present_value, future_value, when);
printf ("Number of payment periods = %f.\n", number_of_periods);
}
Output
Number of payment periods = 70.
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