function randomIRRProblem(form) {
theCF0 = -1000 - (Math.round(Math.random()*2)*100);
theCF1 = ((Math.round(Math.random()*5)) + 1)*100;
theCF2 = ((Math.round(Math.random()*5)) + 1)*100;
theCF3 = ((Math.round(Math.random()*5)) + 1)*100;
theCF4 = ((Math.round(Math.random()*5)) + 1)*100;
theCF5 = ((Math.round(Math.random()*5)) + 1)*100;
form.Year0.value="" + theCF0;
form.Year1.value="" + theCF1;
form.Year2.value="" + theCF2;
form.Year3.value="" + theCF3;
form.Year4.value="" + theCF4;
form.Year5.value="" + theCF5;
form.IRROutput.value="";
}
function calcPV(inFV, inNR, inNP, inC) {
var outPV = inFV*Math.pow((1 + inNR/(100*inC)),(-inNP));
return outPV;
}
function calcIRR(inCFs, inNum) {
if (inNum == 0) return "";
if (inCFs[0] >= 0) return "";
var theSum = 0;
var theGuess = 10;
var theOldGuess = 10;
var theH = 0.001;
var thePV = 0;
var thePVH = 0;
var theDeriv = 0;
var theCnt = 0;
do {
thePV = inCFs[0];
thePVH = inCFs[0];
theSum = inCFs[0];
for (i = 1; i <= inNum; i++) {
theSum += inCFs[i];
thePV += calcPV(inCFs[i],theGuess,i,1);
thePVH += calcPV(inCFs[i],(theGuess + theH),i,1);
}
if (theSum < 0) return "";
theDeriv = (thePVH - thePV)/theH;
if (theDeriv != 0) {
theOldGuess = theGuess;
theGuess = theGuess - thePV/theDeriv;
} else {
return "";
}
theCnt++;
if (theCnt > 50) return "";
} while (Math.abs(thePV) > 0.01)
return theOldGuess;
}
function findIRR(form) {
theCF0Str = form.Year0.value;
if (!isNegativeNumber(theCF0Str)) {
return false;
}
theCF1Str = form.Year1.value;
if (!isPositiveNumber(theCF1Str)) {
return false;
}
theCF2Str = form.Year2.value;
if (!isPositiveNumber(theCF2Str)) {
return false;
}
theCF3Str = form.Year3.value;
if (!isPositiveNumber(theCF3Str)) {
return false;
}
theCF4Str = form.Year4.value;
if (!isPositiveNumber(theCF4Str)) {
return false;
}
theCF5Str = form.Year5.value;
if (!isPositiveNumber(theCF5Str)) {
return false;
}
var theCF = new Array(6);
theCF[0] = parseFloat(theCF0Str);
theCF[1] = parseFloat(theCF1Str);
theCF[2] = parseFloat(theCF2Str);
theCF[3] = parseFloat(theCF3Str);
theCF[4] = parseFloat(theCF4Str);
theCF[5] = parseFloat(theCF5Str);
var theIRR = calcIRR(theCF,5);
form.IRROutput.value = "" + Math.round(theIRR*100)/100;
return true;
}
function calcIRRHelp(form) {
theCF0Str = form.Year0.value;
if (!isNegativeNumber(theCF0Str)) {
return false;
}
theCF1Str = form.Year1.value;
if (!isPositiveNumber(theCF1Str)) {
return false;
}
theCF2Str = form.Year2.value;
if (!isPositiveNumber(theCF2Str)) {
return false;
}
theCF3Str = form.Year3.value;
if (!isPositiveNumber(theCF3Str)) {
return false;
}
theCF4Str = form.Year4.value;
if (!isPositiveNumber(theCF4Str)) {
return false;
}
theCF5Str = form.Year5.value;
if (!isPositiveNumber(theCF5Str)) {
return false;
}
theCF = new Array(6);
theCF2 = new Array(6);
theF = new Array(6);
theCF[0] = parseFloat(theCF0Str);
theCF[1] = parseFloat(theCF1Str);
theCF[2] = parseFloat(theCF2Str);
theCF[3] = parseFloat(theCF3Str);
theCF[4] = parseFloat(theCF4Str);
theCF[5] = parseFloat(theCF5Str);
var theIRR = calcIRR(theCF,5);;
var theNum = 0;
var theCNT = 1;
for (i = 1; i <= 5; i++) {
if (i > 1) {
if (theCF[i] == theCF[i-1]) {
theCF2[theCNT] = theCF[i];
theF[theCNT]++;
} else {
theCNT++;
theCF2[theCNT] = theCF[i];
theF[theCNT] = 1;
}
} else {
theCF2[theCNT] = theCF[i];
theF[theCNT] = 1;
}
}
theIRR = "" + Math.round(theIRR*100)/100;
var theOut = "IRR Help";
theOut += "IRR Help
";
theOut += "To solve using the Texas Instruments BA II Plus Calculator:
";
theOut += "| [CF] | [2nd][CLR WORK] |
";
theOut +="| " + theCF[0] + " | [Enter][Down Arrow] |
";
for (i=1; i<=theCNT; i++) {
theOut +="| " + theCF2[i] + " | [Enter][Down Arrow] |
";
theOut +="| " + theF[i] + " | [Enter][Down Arrow] |
";
}
theOut +="| [IRR] | [CPT] |
";
theOut += "The IRR is " + theIRR + "\%
";
theOut += "";
theOut += "";
theOut += "";
var newWin = window.open("","","scrollbars,resizable,width=400,height=420");
if (newWin != null) {
newWin.document.write(theOut);
newWin.document.close();
newWin.focus();
}
return true;
}
function isPositiveNumber(inputStr) {
for (var i = 0; i < inputStr.length; i++) {
var oneChar = inputStr.substring(i,i+1);
if (((oneChar >= "0") && (oneChar <= "9")) || (oneChar == ".")) {
} else {
alert("Please make sure that only numbers are input.");
return false;
}
}
return true;
}
function isNegativeNumber(inputStr) {
if (inputStr.length < 2) {
alert("Please input a negative number.");
return false;
}
var oneChar = inputStr.substring(0,1);
if (oneChar != '-') {
alert("Please make sure that only negative numbers are input.");
return false;
}
for (var i = 1; i < inputStr.length; i++) {
oneChar = inputStr.substring(i,i+1);
if (((oneChar >= "0") && (oneChar <= "9")) || (oneChar == ".")) {
} else {
alert("Please make sure that only numbers are input.");
return false;
}
}
return true;
}