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 computeHomeAmountForm(form,name)
    {
        if(!chkNumber( getElement('income'), 100, 999999999, "Before Tax Income", "no" ) ||
           !chkNumber( getElement('rate'), 0.01, 19.99, "Mortgage Rate", "no" ) ||
           !chkNumber( getElement('years'), 1, 50, "# of Years", "no" ) ||
           !chkNumber( getElement('downpymt'), 0, 999999, "Down Payment", "yes" ) ) {
            return;
        }

        if (getElement('rate').value < 1.0) {
            getElement('rate').value = getElement('rate').value * 100;
        }

        var months   = getElement('years').value * 12;
        var monthpay = getElement('income').value;
        var downpay  = getElement('downpymt').value == null || getElement('downpymt').value.length == 0
                         ? 0 : getElement('downpymt').value;
        if( monthpay >= 10000 ) { monthpay /= 12.0; }
        monthpay *= 0.28;
        var monthpayrd = round(monthpay,2);
        var loanamt = calculateLoan( monthpay, getElement('rate').value, months );
        var affordamt = round(loanamt - -downpay, 2);
        getElement('monthlypayment').innerHTML="$" + monthpayrd;
        getElement('houseprice').innerHTML="$" + affordamt;

        return true;
    }