function stripNum(num) {
var iPercent
var iDollar
var iSpace
var iComma
var numLength = num.length
if(numLength > 0) {
   num=num.toString();
   iPercent = num.indexOf("%");
   if(iPercent >= 0) {
      num=num.substring(0,iPercent) + "" + num.substring(iPercent + 1,numLength);
      numLength=num.length;
      }
   iDollar = num.indexOf("$");
   if(iDollar >= 0) {
      num=num.substring(0,iDollar) + "" + num.substring(iDollar + 1,numLength);
      numLength=num.length;
      }
   iSpace = num.indexOf(" ");
   if(iSpace >= 0) {
      num=num.substring(0,iSpace) + "" + num.substring(iSpace + 1,numLength);
      numLength=num.length;
      }
   iComma = num.indexOf(",");
   if(iComma >= 0) {
      while(iComma >=1) {
         num=num.substring(0,iComma) + "" + num.substring(iComma + 1,numLength);
         numLength=num.length;
         iComma = num.indexOf(",");
      }
      }
      num = eval(num);
} else {
num = 0;
}
return num;
}
function formatCurrency(num) {
var isNeg=0;
    if(num < 0) {
       num=num*-1;
       isNeg=1;
    }
	onum=Math.round(num*100)/100;
	integer=Math.floor(onum);
	if (Math.ceil(onum) == integer) {
		decimal="00";
	} else{
		decimal=Math.round((onum-integer)*100)
	}
	decimal=decimal.toString();
	if (decimal.length<2) decimal="0"+decimal;
	integer=integer.toString();
	var tmpnum="";
	var tmpinteger="";
	var y=0;
	for (x=integer.length;x>0;x--) {
		tmpnum=tmpnum+integer.charAt(x-1);
		y=y+1;
		if (y==3 & x>1) {
			tmpnum=tmpnum+",";
			y=0;
		}
	}
	for (x=tmpnum.length;x>0;x--) {
		tmpinteger=tmpinteger+tmpnum.charAt(x-1);
	}
	finNum="$"+tmpinteger+"."+decimal;
    if(isNeg == 1) {
       finNum = "-" + finNum;
    }
	return finNum;
}

function computeMonthlyPayment(prin, numPmts, intRate) {
var pmtAmt = 0;
if(intRate == 0) {
   pmtAmt = prin / ( numPmts * 12);
} else {
   if (intRate >= 1.0) {
     intRate = intRate / 100.0;
   }
   intRate /= 12;
   var pow = 1;
   for (var j = 0; j < ( numPmts * 12); j++)
      pow = pow * (1 + intRate);
   pmtAmt = (prin * pow * intRate) / (pow - 1);
}
return pmtAmt;
}

function computeFixedInterestCost(principal, intRate, pmtAmt) { 
   var i = eval(intRate);
   if(i >= 1) {
   i /= 100;
   }
   i /= 12;
   var prin = eval(principal);
   var intPort = 0;
   var accumInt = 0;
   var prinPort = 0;
   var pmtCount = 0;
   var testForLast = 0;

   //CYCLES THROUGH EACH PAYMENT OF GIVEN DEBT
   while(prin > 0) {
      testForLast = (prin * (1 + i));
      if(pmtAmt < testForLast) {
         intPort = prin * i;
         accumInt = eval(accumInt) + eval(intPort);
         prinPort = eval(pmtAmt) - eval(intPort);
         prin = eval(prin) - eval(prinPort);
      } else {
      //DETERMINE FINAL PAYMENT AMOUNT
      intPort = prin * i;
      accumInt = eval(accumInt) + eval(intPort);
      prinPort = prin;
      prin = 0;
      }
      pmtCount = eval(pmtCount) + eval(1);
      if(pmtCount > 1000 || accumInt > 1000000000) {
         prin = 0;
      }
   }
return accumInt;
}

function computeLoan(form) {
if(form.numPmts.value == null || form.numPmts.value.length == 0) {
   alert("Please enter the number of monthly payments.");
   form.numPmts.focus();
} else
if(form.interest.value == null || form.interest.value.length == 0) {
   alert("Please enter the interest rate.");
   form.interest.focus();
} else
if(form.principal.value == null || form.principal.value.length == 0) {
   alert("Please enter the principal (amount borrowed).");
   form.principal.focus();
} else {
var VintRate = stripNum(form.interest.value);
var VnumPmts = stripNum(form.numPmts.value);
var Vprin = stripNum(form.principal.value);
var VpmtAmt = computeMonthlyPayment(Vprin, VnumPmts, VintRate);
var VloanCost = computeFixedInterestCost(Vprin, VintRate, VpmtAmt);
form.payment.value = formatCurrency(VpmtAmt);

//var VloanCost = eval(VpmtAmt * VnumPmts) - eval(Vprin);
form.totalint.value = formatCurrency(VloanCost);
  }
}