Merge branch 'master' of https://github.com/essamjoubori/finance.js

ebradyjobory · Mar 26, 2016 · af30afa · af30afa
2 parents 4309bf9 + f177c02
commit af30afa
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diff --git a/finance.js b/finance.js
@@ -163,6 +163,11 @@ Finance.prototype.WACC = function(marketValueOfEquity, marketValueOfDebt, costOf
   return Math.round(WACC * 1000) / 10;
 };
 
+// PMT calculates the payment for a loan based on constant payments and a constant interest rate
+Finance.prototype.PMT = function(fractionalRate, numOfPayments, principal) {
+  return -principal * fractionalRate/(1-Math.pow(1+fractionalRate,-numOfPayments))
+};
+
 if (typeof exports !== 'undefined') {
   if (typeof module !== 'undefined' && module.exports) {
     module.exports = Finance;

diff --git a/test/index.js b/test/index.js
@@ -101,4 +101,9 @@ describe('FinanceJS', function() {
     cal.WACC(600000, 400000, 6, 5, 35).should.equal(4.9);
   });
 
+  it('should compute PMT', function() {
+    // fractional rate, number of payments, loan principal
+    Number(cal.PMT(0.02,36,-1000000).toFixed(4)).should.equal(39232.8526)
+  });
+
 });