//*******************************************
//Retirement Savings Calculator
//1998 Daniel C. Peterson ALL RIGHTS RESERVED
//Created: 08/21/1998
//Last Modified: 05/23/2002
//This script may not be copied, edited or reproduced
//without express written permission from
//Daniel C. Peterson of Web Winder Website Services
//For commercial use rates, contact:
//Web Winder Website Services
//P.O. Box 11
//Bemidji, MN  56619
//dan@webwinder.com
//http://www.webwinder.com
//Commercial User Licence #:5016-1145-144-1102
//Commercial Licence Date:2007-10-28
//*******************************************

function stripNum(num) {

   num=num.toString();


   var len = num.length;
   var rnum = "";
   var test = "";
   var j = 0;

   var b = num.substring(0,1);
   if(b == "-") {
      rnum = "-";
   }

   for(i = 0; i <= len; i++) {

      b = num.substring(i,i+1);

      if(b == "0" || b == "1" || b == "2" || b == "3" || b == "4" || b == "5" || b == "6" || b == "7" || b == "8" || b == "9" || b == ".") {
         rnum = rnum + "" + b;

      }

   }

   if(rnum == "" || rnum == "-") {
      rnum = 0;
   }

   rnum = Number(rnum);

   return rnum;

}

function formatNumber(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 computeForm(form) {

if (form.payments.value == null || form.payments.value.length == 0) {
   alert("Please enter the number of years you would like to make monthly withdrawels from your investment.");
   form.payments.focus();
} else
if(form.interest.value == null || form.interest.value.length == 0) {

   alert("Please enter the annual interest rate you expect to earn from your investment.");
   form.interest.focus();
} else
if(form.principal.value == null || form.principal.value.length == 0) {

   alert("Please enter the amount you would like to withdraw each month.");
   form.principal.focus();
} else {


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

    if (i >= 1.0) {

        i = i / 100.0;
        } else {
        i = i;
    }

   i = i /12

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

   var nPer = stripNum(form.payments.value);
   nPer *= 12;

   var count = 0;

   var factor = eval(1) + eval(i);

   var denom = 1;

    while(count < nPer) {
       denom = denom * factor;
        count = eval(count) + eval(1);
        }

    var Vpv = eval(1) - eval(1 / denom);

    Vpv = Vpv / i;

    Vpv = prin * Vpv;

    form.pv.value = "$" + formatNumber(Vpv);

    }
}