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 formatNumberDec(num, places, comma) {

var isNeg=0;

    if(num < 0) {
       num=num*-1;
       isNeg=1;
    }

    var myDecFact = 1;
    var myPlaces = 0;
    var myZeros = "";
    while(myPlaces < places) {
       myDecFact = myDecFact * 10;
       myPlaces = eval(myPlaces) + eval(1);
       myZeros = myZeros + "0";
    }
    
	onum=Math.round(num*myDecFact)/myDecFact;
		
	integer=Math.floor(onum);

	if (Math.ceil(onum) == integer) {
		decimal=myZeros;
	} else{
		decimal=Math.round((onum-integer)* myDecFact)
	}
	decimal=decimal.toString();
	if (decimal.length<places) {
        fillZeroes = places - decimal.length;
	   for (z=0;z<fillZeroes;z++) {
        decimal="0"+decimal;
        }
     }

   if(places > 0) {
      decimal = "." + decimal;
   }

   if(comma == 1) {
	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;
   } else {
      finNum=integer+""+decimal;
   }

    if(isNeg == 1) {
       finNum = "-" + finNum;
    }

	return finNum;
}


function computeForm(form) {

if (form.principal.value == null || form.principal.value.length == 0) {
   alert("Please enter the loan's principal amount.");
   form.principal.focus();
} else
if (form.interest_rate.value == null || form.interest_rate.value.length == 0) {
   alert("Please enter the loan's annual interest rate.");
   form.interest_rate.focus();
} else
if (form.num_years.value == null || form.num_years.value.length == 0) {
   alert("Please enter the loan's term in number of years.");
   form.num_years.focus();
} else
if (form.ppy.value == null || form.ppy.value.length == 0) {
   alert("Please enter the number of payments per year.");
   form.ppy.focus();
} else {

   var Vprincipal = stripNum(form.principal.value);

   var i = stripNum(form.interest_rate.value);

    if (i >= 1.0) {

        i = i / 100.0;

    }

   var Vnum_years = stripNum(form.num_years.value);
   var Vppy = stripNum(form.ppy.value);
   var num_pmts = Vnum_years * Vppy;

    i /= Vppy;

    var pow = 1;

    for (var j = 0; j < num_pmts; j++)

        pow = pow * (1 + i);

     var Vpayment = (Vprincipal * pow * i) / (pow - 1);

    form.payment.value = "$" + formatNumberDec(Vpayment,2,1);

    var Vtotalint = ((Vpayment * num_pmts) - Vprincipal);

   form.totalint.value = "$" + formatNumberDec(Vtotalint,2,1);
   }
}

function clearResults(form) {

form.payment.value = "";
form.totalint.value = "";

}