//Copyright 2000. Compendium Research Corporation. All Rights Reserved.
var bDebug = 0; // change to 1 for extra output
var sNl = "\r";
var sOut = ""; // html output string
var nErrorNumber = -1.2345e-12;
var sSub = "%s";
var iStopMonths = 12 * 300; // approximate length after this
var bLongTest = false; // if true, init for long test
var shStart = "" + sNl
+ "%s" + sNl
+ "" + sNl
+ "" + sNl
+ "" + sNl
+ "";
var shHeading1 = "
" + sNl
+ "
"
+ "%s
";
var shHeadGif = "
" + sNl
+ "
";
var shHeading2 = "
" + sNl
+ "
"
+ "%s
";
var shBeginTable1 =
"
";
var shEndTable = "
";
var shBeginRow = "
";
var shEndRow = "
";
var shCell1 = "
%s
";
var shCell2 = "
%s
";
var shCell3 = "
%s
";
var shEndPage = "
Back";
function EmitRow1(s2, s3)
{
Emit(shBeginRow);
Emit1(shCell1, " ");
Emit1(shCell1, s2);
Emit1(shCell1, s3);
Emit(shEndRow);
}
function EmitRow2(s1,s2,s3)
{
Emit(shBeginRow);
Emit1(shCell2, s1);
Emit1(shCell3, s2);
Emit1(shCell3, s3);
Emit(shEndRow);
}
function Initialize(f)
{
if (bLongTest)
{
f.appo0001.value=100000; // beg balance
f.appo0002.value=250.01; // min monthly payment
f.appo0003.value=500; // max monthly payment
f.appo0004.value=3; // interest rate
}
}
function Execute(oForm)
{
var iError = 0;
var nPrincipal, nInputInterest, iYears;
var nMinPayment, nMaxPayment;
if ( (nPrincipal = Validate(oForm.appo0001.value, 0)) == nErrorNumber)
iError = 100;
else if ( (nMinPayment = Validate(oForm.appo0002.value, 0)) == nErrorNumber)
iError = 110;
else if ( (nMaxPayment = Validate(oForm.appo0003.value, 0)) == nErrorNumber)
iError = 120;
else if ( (nInputInterest = Validate(oForm.appo0004.value, 0)) == nErrorNumber)
iError = 130;
var iPpy = 12;
// var iMonths = 12 * iYears;
// var iPeriods = iPpy * iYears;
var nPercent = nInputInterest / iPpy / 100;
if (!iError)
{
var sMessage = "";
if (nPrincipal == 0)
sMessage = "Please enter a beginning balance";
else if (nPrincipal < 0)
sMessage = "Beginning balance must be positive";
else if (nMinPayment == 0)
sMessage = "Please enter a minimum monthly payment";
else if (nMinPayment < 0)
sMessage = "Minimum monthly payment must be positive";
else if (nMaxPayment == 0)
sMessage = "Please enter a maximum monthly payment";
else if (nMaxPayment < 0)
sMessage = "Maximum monthly payment must be positive";
else if (nPercent == 0)
sMessage = "Please enter an interest rate (%)";
else if (nPercent < 0)
sMessage = "Interest rate (%) must be positive";
else if (nMinPayment > nMaxPayment)
sMessage = "Minimum monthly payment must be smaller "
+ "than maximum monthly payment";
else if (nMinPayment <= nPrincipal * nPercent)
sMessage = "Minimum monthly payment is too"
+ " small because it is less than the monthly"
+ " interest required by this loan";
if (sMessage != "")
{
iError = 170;
alert(sMessage);
}
}
if (!iError)
{
var iK, iN;
var nFraction = 0;
var nBalance = nPrincipal;
var nInterest, nReduction;
var iMonths1 = 0, iMonths2 = 0;
var nTotalInt1, nTotalInt2;
for (iN = 1; iN >= 0; --iN)
{
nPayment = iN ? nMinPayment : nMaxPayment;
nFraction = 0;
nBalance = nPrincipal;
iMonths2 = 0;
nTotalInt2 = 0;
for (iK = 1; !iMonths2 && iK <= iStopMonths; ++iK)
{
nInterest = nBalance * nPercent + nFraction;
nFraction = nInterest - Round(nInterest,2);
nInterest = Round(nInterest,2);
if (nPayment > nBalance + nInterest)
{
nPayment = nBalance + nInterest;
iMonths2 = iK;
}
nReduction = nPayment - nInterest;
nBalance -= nReduction;
nTotalInt2 += nInterest;
}
if (!iMonths2) // looping algorithm failed
{
nPayment = iN ? nMinPayment : nMaxPayment;
iMonths2 = Math.floor(
Math.log(1-nPercent*nPrincipal / nPayment)
/ Math.log(1 - nPercent)) - 1;
nTotalInt2 = nPayment * iMonths2 - nPrincipal;
}
if (iN)
{
nTotalInt1 = nTotalInt2;
iMonths1 = iMonths2;
}
}
var nAvgInt1 = Round(nTotalInt1 / iMonths1, 2);
var nAvgInt2 = Round(nTotalInt2 / iMonths2, 2);
var nYears1 = Round(iMonths1/iPpy, 3);
var nYears2 = Round(iMonths2/iPpy, 3);
Emit1(shStart, "Loan Length Calculator Results<\/span>");
// Emit1(shHeadGif, "gifs/loan_length_calc_results.gif");
Emit1(shHeading1, "Loan Length Calculator Results<\/span>");
Emit1(shHeading2, "LOAN LENGTH COMPARISON<\/span>");
Emit(shBeginTable1);
EmitRow1("Minimum Monthly Payment", "Maximum Monthly Payment");
EmitRow2("Monthly Payment", DollarFormat(nMinPayment, 0, 2),
DollarFormat(nMaxPayment, 0, 2));
EmitRow2("Beginning Balance of Loan",
DollarFormat(nPrincipal, 0, 2),
DollarFormat(nPrincipal, 0, 2));
EmitRow2("Interest Rate (%) (fixed loan)", nInputInterest + " %",
nInputInterest + " %");
EmitRow2("Average Monthly Interest",
DollarFormat(nAvgInt1, 0, 2),
DollarFormat(nAvgInt2, 0, 2));
EmitRow2("Total Interest",
DollarFormat(nTotalInt1, 0, 2),
DollarFormat(nTotalInt2, 0, 2));
EmitRow2("Loan Length in Months", iMonths1 + " Months",
iMonths2 + " Months");
EmitRow2("Loan Length in Years", Format(nYears1, 0, 3) + " Years",
Format(nYears2, 0, 3) + " Years");
Emit(shEndTable);
Emit(shEndPage);
}
if (!iError)
{
// document.open();
document.write(sOut);
document.close();
}
}
function Emit(sStr) { sOut += sStr + sNl; }
function Emit1(sStr, s1)
{
var iK;
if ( (iK = sStr.indexOf(sSub)) >= 0)
sStr = sStr.substring(0, iK) + s1
+ sStr.substring(iK + sSub.length);
Emit(sStr);
}
function Emitx(sStr, sSubs)
{
var iK, iL, iPos1 = 0, iPos2 = 0;
while ( (iK = sStr.indexOf(iPos1, sSub)) >= 0)
{
if ( (iL = eSubs.indexOf(iPos2, sSep)) < 0)
iL = eSubs.length();
sStr = sStr.substring(0, iK)
+ sSubs.substring(iPos1, iL)
+ sStr.substring(iK + sSub.length());
iPos1 = iK + sSub.length();
if ( (iPos2 = iL + eSep.length()) > sSubs.length())
iPos2 = sSubs.length();
}
Emit(sStr);
}
var sBlanks = " "
+ " ";
var sDashes = "---------------------------------------------"
+ "-----------------------------------------";
var nPowers = [
0.0000000000000001,
0.000000000000001,
0.00000000000001,
0.0000000000001,
0.000000000001,
0.00000000001,
0.0000000001,
0.000000001,
0.00000001,
0.0000001,
0.000001,
0.00001,
0.0001,
0.001,
0.01,
0.1,
1.,
10.,
100.,
1000.,
10000.,
100000.,
1000000.,
10000000.,
100000000.,
1000000000.,
10000000000.];
function Power(n)
{
return nPowers[n+16];
}
var sMonths = ["January", "February", "March", "April", "May",
"June", "July", "August", "September", "October",
"November", "December"];
function Mmm(iK) { if (!(iK >= 1 && iK <= 12)) return "MMM" + iK;
return sMonths[iK-1].substring(0, 3); }
function ExpN(nX, iN) // compute x ** n, where n is integral
{
var nResult = 1;
var bSign = 0;
if (iN < 0)
{
bSign = 1;
iN = -iN;
}
while (iN > 0)
{
if (iN & 1)
nResult *= nX;
nX *= nX;
iN >>= 1;
}
if (bSign)
nResult = 1 / nResult;
return nResult;
}
function PresentValue(nPayment, nPercent, iNumPeriods)
{
var nAmount = (Math.abs(nPercent) > 1e-20)
? nPayment * (1 - ExpN(1 + nPercent, -iNumPeriods))
/ nPercent
: nPayment * iNumPeriods;
return nAmount;
}
function SparsePresentValue(nPayment, nPercent, iInterval, iNumPeriods)
{
var nAmount = (Math.abs(nPercent) > 1e-20)
? nPayment * (1 - ExpN(1 + nPercent, -iNumPeriods))
/ (ExpN(1 + nPercent, iInterval) - 1)
: nPayment * iNumPeriods;
return nAmount;
}
function Round(nVal, iD)
{
var iSign = 1;
if (nVal < 0)
{
nVal = - nVal;
iSign = -1;
}
var iInt = Math.round(nVal);
if (iD > 0)
iInt = Math.floor(nVal);
var nFp = nVal - iInt;
// alert ('iInt, nFp = ' + iInt + ", " + nFp);
if (iD > 0)
nFp = Math.round(nFp * Power(iD)) / Power(iD);
nVal = iSign * (iInt + nFp);
return nVal;
}
function Validate(sVal, bInt)
{
var sMessage = "";
var bDot = 0, bE = 0, iState = 0;
var sCh, iK;
var bInvalid = 0;
var nValue = bInt ? parseInt(sVal) : parseFloat(sVal);
for (iK = 0; sMessage == "" && iK < sVal.length; ++iK)
{
sCh = sVal.charAt(iK);
if (sCh == " ")
{
if (iState > 0)
iState = 9;
}
else
{
if (iState == 9)
sMessage = "Number '" + sVal + "' has an embedded blank";
else if (sCh == '.' && !bInt)
{
if (bDot || bE)
bInvalid = 1;
else
bDot = 1;
}
else if ((sCh == 'e' || sCh == 'E') && !bInt)
{
if (bE)
bInvalid = 1;
else
{
bE = 1;
iState = 6;
}
}
else if (sCh == '+' || sCh == '-')
{
if (iState == 0 || iState == 6)
++iState;
else
sMessage = "Number '" + sVal + "' contains a sign "
+ "in an illegal position"
}
else if (sCh >= '0' && sCh <= '9')
{
if (iState == 1 || iState == 7)
++iState;
else if (iState == 0 || iState == 6)
iState += 2;
}
else
bInvalid = 1;
}
if (bInvalid)
sMessage = "Number '" + sVal + "' contains"
+ " invalid non-numeric character(s)";
}
if (sMessage == "")
if (iState == 1 || iState == 6 || iState == 7)
sMessage = "Illegal number: " + sVal;
else if (iState == 0)
nValue = 0;
if (sMessage != "")
{
alert(sMessage);
nValue = nErrorNumber;
}
return nValue
}
// DollarFormat -- could be jazzed up to produce "CR" or "DB"
function DollarFormat(nVal, iW, iD)
{
return GenFmt(nVal, iW, iD, 1);
}
function Format(nVal, iW, iD)
{
return GenFmt(nVal, iW, iD, 0);
}
function GenFmt(nVal, iW, iD, bDollar) // format val into w chars,
// d digs after decimal point
{
var sOut = "";
var iSign = 0;
nVal = Round(nVal, iD);
if (nVal < 0)
{
nVal = - nVal;
iSign = 1;
}
var iInt = Math.round(nVal);
if (iD > 0)
iInt = Math.floor(nVal);
var nFp = nVal - iInt;
var iDigs = 1;
if (iInt > 9)
iDigs = Math.floor(Math.log(iInt+.1)/Math.log(10)) + 1;
var iLeft = iW - iSign - (bDollar ? 1 : 0);
if (iD > 0)
iLeft -= iD + 1;
if (iLeft > iDigs)
sOut += sBlanks.substring(0, iLeft - iDigs);
if (iSign)
sOut += '-';
if (bDollar)
sOut += '$';
sOut += iInt;
if (iD > 0)
{
nFp = Math.round((1 + nFp) * Power(iD));
sOut += '.' + String(nFp).substring(1);
}
return sOut;
}
function PrepadString(sStr, iW)
{
if (sStr.length < iW)
sStr = sBlanks.substring(0, iW - sStr.length) + sStr;
return sStr;
}
function CenterString(sStr, iW)
{
var iBlanks = iW - sStr.length;
if (iBlanks > 0)
sStr = sBlanks.substring(0, Math.floor(iBlanks/2)) + sStr
+ sBlanks.substring(0, iBlanks - Math.floor(iBlanks/2));
return sStr;
}