function switchyrs(form) { form.years.value = eval((form.months.value)/12) } function roundtopennies(n) { pennies = n * 100; pennies = Math.round(pennies); strPennies = "" + pennies; len = strPennies.length; return strPennies.substring(0, len - 2) + "." + strPennies.substring(len-2, len); } function roundtopennies2(n) { pennies = n * 10000; pennies = Math.round(pennies); strPennies = "" + pennies; len = strPennies.length; return strPennies.substring(0, len - 2) + "." + strPennies.substring(len-2, len); } function monthly(principal, years, apr) { rate = apr/12; payments = years * 12; return roundtopennies(principal * rate / (1 - (1/Math.pow(1 + rate, payments)))); } function monthlyamortization(principal, years, apr) { payments = years * 12; monthlyinterest = apr/12; monthlypayment = monthly(principal, years, apr); //popnewwindow.document.open(); if(document.getElementById('no').checked){ var popnewwindow = "Your Payments

Amortization Table

"; popnewwindow = popnewwindow + ""; popnewwindow = popnewwindow + ""; popnewwindow = popnewwindow + ""; popnewwindow = popnewwindow + ""; popnewwindow = popnewwindow + ""; //popnewwindow.document.write(""); popnewwindow = popnewwindow + ""; popnewwindow = popnewwindow + ""; popnewwindow = popnewwindow + ""; //popnewwindow.document.write(""); popnewwindow = popnewwindow + ""; popnewwindow = popnewwindow + ""; popnewwindow = popnewwindow + ""; popnewwindow = popnewwindow + ""; popnewwindow = popnewwindow + ""; for(i = 1; i <= payments; i++) { popnewwindow = popnewwindow + ""; popnewwindow = popnewwindow + ""; interestpayment= principal * monthlyinterest; popnewwindow = popnewwindow + ""; principalpayment = monthlypayment - interestpayment; popnewwindow = popnewwindow + ""; principal = principal - principalpayment; popnewwindow = popnewwindow + ""; popnewwindow = popnewwindow + "
"; popnewwindow = popnewwindow + "$" + roundtopennies(principal); popnewwindow = popnewwindow + " at " + roundtopennies2(apr) + "%"; popnewwindow = popnewwindow + " over " + years + " years.
"; popnewwindow = popnewwindow + "Monthly payments: $" + monthly(principal, years, apr); popnewwindow = popnewwindow + "
Payments
MonthInterestPrincipalBalance
" + i + "$" + roundtopennies(interestpayment) + "$" + roundtopennies(principalpayment) + "$" + roundtopennies(principal) + ""; } popnewwindow = popnewwindow + "
"; //popnewwindow.document.close(); document.getElementById("resultspan").innerHTML = popnewwindow; //popnewwindow.focus(); } if(document.getElementById('yess').checked){ var x="Total Interest: $" + ((monthly(principal, years, apr)*years*12)-(principal)); var oResult=document.getElementById("theresult"); var oResultLine=document.getElementById("resultLine"); oResultLine.style.visibility="visible"; oResult.innerHTML = x; var popnewwindow = "Your Payments

Amortization Table

"; popnewwindow = popnewwindow + ""; popnewwindow = popnewwindow + ""; popnewwindow = popnewwindow + ""; popnewwindow = popnewwindow + ""; popnewwindow = popnewwindow + ""; //popnewwindow.document.write(""); popnewwindow = popnewwindow + ""; popnewwindow = popnewwindow + ""; popnewwindow = popnewwindow + ""; //popnewwindow.document.write(""); popnewwindow = popnewwindow + ""; popnewwindow = popnewwindow + ""; popnewwindow = popnewwindow + ""; popnewwindow = popnewwindow + ""; popnewwindow = popnewwindow + ""; for(i = 1; i <= payments; i++) { popnewwindow = popnewwindow + ""; popnewwindow = popnewwindow + ""; interestpayment= principal * monthlyinterest; popnewwindow = popnewwindow + ""; principalpayment = monthlypayment - interestpayment; popnewwindow = popnewwindow + ""; principal = principal - principalpayment; popnewwindow = popnewwindow + ""; popnewwindow = popnewwindow + "
"; popnewwindow = popnewwindow + "$" + roundtopennies(principal); popnewwindow = popnewwindow + " at " + roundtopennies2(apr) + "%"; popnewwindow = popnewwindow + " over " + years + " years.
"; popnewwindow = popnewwindow + "Monthly payments: $" + monthly(principal, years, apr); popnewwindow = popnewwindow + "
Payments
MonthInterestPrincipalBalance
" + i + "$" + roundtopennies(interestpayment) + "$" + roundtopennies(principalpayment) + "$" + roundtopennies(principal) + ""; } popnewwindow = popnewwindow + "
"; //popnewwindow.document.close(); document.getElementById("resultspan").innerHTML = popnewwindow; } } function compute(form) { if((form.principal.value.length != 0) && (form.apr.value.length != 0) && (form.years.value.length != 0)) { principal = eval(form.principal.value); apr = eval(form.apr.value)/100.0; years = eval(form.years.value); if(years == 0.0) { alert("you have no monthly payments, since the number of years is zero."); } else { monthlyamortization(principal, years,apr); } } else { alert("You must fill in all the fields before calculating."); } }