function chkNumber(input, min, max, fieldName, mayBeBlank )

{

    msg = 'The ' + fieldName + ' field';



    if( input.value == null || input.value.length == 0 ) {

        if( mayBeBlank == "yes" ) return true;

        alert( msg + ' must be filled in!' );

        input.focus();

        input.select();

        return false;

    }



    var str = input.value;

    for (var i = 0; i < str.length; i++) {

        var ch = str.substring(i, i+1);

        if ((ch < "0" || "9" < ch) && ch != '.') {

           if( ch != '%' || i != str.length-1 ) {

               alert( msg + ' has a non-numeric character' );

               input.focus(); input.select();

               return false;

           }

        }

    }

    var num = parseFloat( str )

    if (num < min || max < num) {

        alert( msg + ' must be between [' + min + ".." + max + "]");

        input.focus();  // new - puts user in error field

        input.select(); // new

        return false;

    }

    return true;

}





    function round(value, places) {

        var multi, chars;



        chars = (places == 0 ? 0 : places+1);



        var str = "" + value;



        for (var i = 0; (str.substring(i,i+1) != "." && i < str.length); ++i)

            ;



        if( str.length == 0 )

            return str;



        str = str + (i < str.length ? "00000000" : ".00000000");



        if( i < 4 )

            return( str.substring( 0, i+chars ) );





        var retstr = "";

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

             if( j != 0 && (i-j) % 3 == 0 ) retstr = retstr + ",";

             retstr = retstr + str.substring( j, j+1 );

        }

        retstr = retstr + str.substring( i, i+chars );

        return retstr;

    }



    function calculateLoan( pmt, rate, months )

    {

        if( rate <= 0 ) {

            return "0.00";

        }

        rate /= 1200.0;

        var power=1.0;

        for (var i=0;++i<=months; power *= (1+rate) ) ;



        return pmt / (rate/(1-(1/power)))

    }



function computeForm(form,name)

{

    if(!chkNumber( form.income, 100, 999999999, "After Tax Income", "no" ) ||

       !chkNumber( form.rate, 0.01, 19.99, "Mortgage Rate", "no" ) ||

       !chkNumber( form.years, 1, 50, "# of Years", "no" ) ||

       !chkNumber( form.downpymt, 0, 999999, "Down Payment", "yes" ) ) {

        return;

    }



   /* if (form.rate.value < 1.0) {

        form.rate.value = form.rate.value * 100;

    }*/
	


    var months   = form.years.value * 12;

    var monthpay = form.income.value;

    var downpay  = form.downpymt.value == null || form.downpymt.value.length == 0

                     ? 0 : form.downpymt.value;

    if( monthpay >= 10000 ) { monthpay /= 12.0; }

    monthpay *= 0.28;

    var loanamt = calculateLoan( monthpay, form.rate.value, months );

	var content_result; 

    content_result = '<p>With your income, you can afford a monthly payment of $' + round( monthpay, 2 ) + '.<br>' ;

     content_result +=  'This translates to a ' + form.years.value + '-year, ' + form.rate.value + '% mortgage of $' + round( loanamt, 2 ) ;

     content_result +=  '.<br>You can therefore buy a house of up to <b>$' +

                  round( loanamt - -downpay, 2 ) + '</b>.' ;

     content_result +=  '<p><b>*Note</b> This calculator uses the common banking figure of 28% when calculating' ;

     content_result +=  ' how much of your income can be spent on housing. This figure may be higher or lower ' ;

     content_result +=  'depending on the amount of debt you are carrying, the area of the country you are buying ' ;

     content_result +=  'housing in, and other factors. Please contact your banker for more information.';

	document.getElementById('cal_result').innerHTML = content_result;



}