jjrdev · January 12, 2018 13:34 · Jan 12, 2018 · Jan 12, 2018 · Jan 12, 2018 · Jan 22, 2013
diff --git a/IRR.js b/IRR.js
@@ -23,7 +23,7 @@
  * 
  *************************************************************/
 
-function IRR(values, guess) {
+export function IRR(values, guess) {
   // Credits: algorithm inspired by Apache OpenOffice
 
   // Calculates the resulting amount

diff --git a/package.json b/package.json
@@ -1,4 +1,4 @@
 {
-  "name": "IRR",
+  "name": "ghalimiirr",
   "version": "0.1.0"
 }
diff --git a/package.json b/package.json
@@ -0,0 +1,4 @@
+{
+  "name": "IRR",
+  "version": "0.1.0"
+}
diff --git a/IRR.js b/IRR.js
@@ -0,0 +1,89 @@
+// Copyright (c) 2012 Sutoiku, Inc. (MIT License)
+
+// Some algorithms have been ported from Apache OpenOffice:
+
+/**************************************************************
+ * 
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ * 
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ * 
+ *************************************************************/
+
+function IRR(values, guess) {
+  // Credits: algorithm inspired by Apache OpenOffice
+
+  // Calculates the resulting amount
+  var irrResult = function(values, dates, rate) {
+    var r = rate + 1;
+    var result = values[0];
+    for (var i = 1; i < values.length; i++) {
+      result += values[i] / Math.pow(r, (dates[i] - dates[0]) / 365);
+    }
+    return result;
+  }
+
+  // Calculates the first derivation
+  var irrResultDeriv = function(values, dates, rate) {
+    var r = rate + 1;
+    var result = 0;
+    for (var i = 1; i < values.length; i++) {
+      var frac = (dates[i] - dates[0]) / 365;
+      result -= frac * values[i] / Math.pow(r, frac + 1);
+    }
+    return result;
+  }
+
+  // Initialize dates and check that values contains at least one positive value and one negative value
+  var dates = [];
+  var positive = false;
+  var negative = false;
+  for (var i = 0; i < values.length; i++) {
+    dates[i] = (i === 0) ? 0 : dates[i - 1] + 365;
+    if (values[i] > 0) positive = true;
+    if (values[i] < 0) negative = true;
+  }
+
+  // Return error if values does not contain at least one positive value and one negative value
+  if (!positive || !negative) return '#NUM!';
+
+  // Initialize guess and resultRate
+  var guess = (typeof guess === 'undefined') ? 0.1 : guess;
+  var resultRate = guess;
+
+  // Set maximum epsilon for end of iteration
+  var epsMax = 1e-10;
+
+  // Set maximum number of iterations
+  var iterMax = 50;
+
+  // Implement Newton's method
+  var newRate, epsRate, resultValue;
+  var iteration = 0;
+  var contLoop = true;
+  do {
+    resultValue = irrResult(values, dates, resultRate);
+    newRate = resultRate - resultValue / irrResultDeriv(values, dates, resultRate);
+    epsRate = Math.abs(newRate - resultRate);
+    resultRate = newRate;
+    contLoop = (epsRate > epsMax) && (Math.abs(resultValue) > epsMax);
+  } while(contLoop && (++iteration < iterMax));
+
+  if(contLoop) return '#NUM!';
+
+  // Return internal rate of return
+  return resultRate;
+}