PERIODS()
Number of periods for a loan
- Syntax
-
- PERIODS (nLoan, nPayment, nInterest) --> nPeriods
- Arguments
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- <nLoan> amount of money you get from the bank <nPayment> amount of money you pay back per period <nInterest> rate of interest per period, 1 == 100%
- Returns
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- <nPeriods> number of periods you need to pay the loan back
- Description
-
- PERIODS() calculates the number of periods one needs to pay back a loan of <nLoan> with periodical payments of <nPayment> and for a rate of interest <nInterest> per period. debt in period 0 = <nLoan> debt in period 1 = ((debt in period 0)-<nPayment>)*(1+<nInterest>/100) debt in period 2 = ((debt in period 1)-<nPayment>)*(1+<nInterest>/100) etc... debt in period <nPeriod> = ((debt in period <nPeriod>-1)-<nPayment>)*(1+<nInterest>/100) -> has to be 0, so <nPeriods> = -log(1-<nLoan>*(<nInterest>/100)/<nPayment>)/log(1+<nInterest>/100))
- Note, however that in the case of nPayment <= <nLoan>*(<nInterest>/100), one would need infinite time to pay the loan back. The functions does then return -1.
Examples
// You get a loan of 5172.56 at a interest rate of 0.5% per
// month (6% per year).
// You can afford to pay 100 back every month, so you need
? periods (5172.56, 100, 0.005) --> 60.0
// months to cancel the loan.
Tests
periods (5172.56, 100, 0.005) == 60.0
periods (5172.56, 100, 0.0) == 51.7256
- Status
- Ready
- Compliance
-
- PERIODS() is compatible with CT3's PERIODS().
- Platforms
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- All
- Files
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- Source is finan.c, library is libct.
- See Also