VINTSCHED

The VINTSCHED function calculates the interest portion of the payments on a series of variable-rate installment loans that are paid off over a specified number of time periods. VINTSCHED calculates the result for a given time period as the sum of the interest due on each loan that is incurred or outstanding in that period. For each time period, you specify the initial amount of the loans incurred in that time period and the interest rate that is charged in that time period for each new or outstanding loan.

Return Value

DECIMAL

The result returned by the VINTSCHED function is dimensioned by the union of all the dimensions of loans and rates and the dimension that is used as the time-dimension argument.

Syntax

VINTSCHED(loans, rates, n, [time-dimension] [STATUS])

Parameters

loans: A numeric expression that contains the initial amounts of the loans. When loans does not have a time dimension, or when loans is dimensioned by multiple time dimensions, the time-dimension argument is required.
rates: A numeric expression that contains the interest rates charged for loans. When rates is a dimensioned variable, it can be dimensioned by any dimension, including a different time dimension. When rates is dimensioned by a time dimension, you specify the interest rate in each time period that applies to the loans incurred or outstanding in that period. The interest rates are expressed as decimal values; for example, a 5 percent rate is expressed as .05.
n: A numeric expression that specifies the number of payments required to pay off the loans in the series. The n expression can be dimensioned, but it cannot be dimensioned by the time dimension argument. One payment is made in each time period of the time dimension by which loans is dimensioned or in each time period of the dimension specified in the time-dimension argument. For example, one payment a month is made when loans is dimensioned by month.
time-dimension: The name of the dimension along which the interest payments are calculated. When loans has a dimension of type of DAY, WEEK, MONTH, QUARTER, or YEAR, the time-dimension argument is optional, unless loans has multiple dimensions of these types.
STATUS: Specifies that VINTSCHED should use the current status list (that is, only the dimension values currently in status in their current status order) when computing the interest portion of the payments. By default VINTSCHED uses the default status list.

Usage Notes

VINTSCHED and NA Values

When loans has a value other than NA and the corresponding value of rates is NA, an error occurs.

VINTSCHED is affected by the NASKIP option. When NASKIP is set to YES (the default), and a loan value is NA for the affected time period, the result returned by VINTSCHED depends on whether the corresponding interest rate has a value of NA or a value other than NA. Table 8-21, "How NASKIP Affects the Results When a Loan or Rate Value is NA for a Given Time Period" illustrates how NASKIP affects the results when a loan or rate value is NA for a given time period.

Table 8-21 How NASKIP Affects the Results When a Loan or Rate Value is NA for a Given Time Period

Loan Value	Rate Value	Result when NASKIP = YES	Result when NASKIP = NO
Non-`NA`	`NA`	Error	Error
`NA`	Non-`NA`	Interest values (`NA` loan value is treated as zero)	`NA` for affected time periods
`NA`	`NA`	`NA` for affected time periods	`NA` for affected time periods

As an example, suppose a loan expression and a corresponding interest expression both have NA values for 1997, but both have values other than NA for succeeding years. When the number of payments is 3, VINTSCHED returns NA for 1997, 1996, and 1995. For 1997, VINTSCHED returns the interest portion of the payment due for loans incurred in 1995, 1996, and 1997.

VINTSCHED Ignores the Status of a Time Dimension

The VINTSCHED calculation begins with the first value of the time dimension, regardless of how the status of that dimension may be limited. For example, suppose loans is dimensioned by year, and the values of year range from Yr95 to Yr99. The calculation always begins with Yr95, even when you limit the status of year so that it does not include Yr95.

However, when loans is not dimensioned by the time dimension, the VINTSCHED calculation begins with the first value in the current status of the time dimension. For example, suppose loans is not dimensioned by year, but year is specified as time-dimension. When the status of year is limited to Yr97 to Yr99, the calculation begins with Yr97 instead of Yr95.

Examples

Example 8-164 Using VINTSCHED

The following statements create two variables called loans and rates.

DEFINE loans DECIMAL <year>
DEFINE rates DECIMAL <year>

Suppose you assign the following values to the variables loans and rates.

YEAR             LOANS      RATES
-------------- ---------- ----------
Yr95               100.00       0.05
Yr96               200.00       0.06
Yr97               300.00       0.07
Yr98                 0.00       0.07
Yr99                 0.00       0.07

For each year, loans contains the initial value of the variable-rate loan incurred during that year. For each year, the value of rates is the interest rate that is charged for that year on any loans incurred or outstanding in that year.

The following statement specifies that each loan is to be paid off in three payments, calculates the interest portion of the payments on the loans,

REPORT W 20 HEADING 'Payment' VINTSCHED(loans, rates, 3, year)

and produces the following report.

YEAR                        Payment
-------------- --------------------
Yr95                           5.00
Yr96                          16.10
Yr97                          33.06
Yr98                          19.43
Yr99                           7.48

The interest payment for 1995 is interest on the loan of $100 incurred in 1995, at 5 percent. The interest payment for 1996 is the sum of the interest on the remaining principal of the 1995 loan, plus interest on the loan of $200 incurred in 1996; the interest rate for both loans is 6 percent. The 1997 interest payment is the sum of the interest on the remaining principal of the 1995 loan, interest on the remaining principal of the 1996 loan, and interest on the loan of $300 incurred in 1997; the interest rate for all three loans is 7 percent. Because the 1995 loan is paid off in 1997, the payment for 1998 represents 7 percent interest on the remaining principal of the 1996 and 1997 loans. In 1999, the interest payment is on the remaining principal of the 1997 loan.