var

	loan,

	interestRate,

	period,

	reward=0;

	

function formatMoney(inVal){

	strIn = new String(inVal);

	if ( strIn.indexOf(".") == -1 ){

		dollar = strIn;

		cent = "";

	}else{

		dollar = strIn.substring(0,strIn.indexOf("."));

		cent = strIn.substring(strIn.indexOf("."),strIn.length);

	}

	count = dollar.length%3;

	if ( count == 0 ){

		count = 3;

	}

	result = dollar.substring(0,count);

	count += 3;

	while ( count <= dollar.length ){

		result += ",";

		result += dollar.substring(count-3,count);

		count += 3;

	}

	result += cent;

	return result;

}



function changeLoan(){

	loan = parseInt(document.forms[1].loan.value);

	if ( isNaN(eval(loan)) ){

		document.forms[1].loan.focus();

		document.forms[1].loan.select();

		alert("Invalid input");

		return false;

	}else{

		document.forms[1].loan.value = loan;

		return true;

	}

}

function changeInterestRate(){

	interestRate = parseFloat(document.forms[1].interestRate.value);

	if ( isNaN(eval(interestRate)) ){

		document.forms[1].interestRate.focus();

		document.forms[1].interestRate.select();

		alert("Invalid input");

		return false;

	}else{

		document.forms[1].interestRate.value = interestRate;

		return true;

	}

}

function changePeriod(){

	period = parseInt(document.forms[1].period.value);

	if ( isNaN(eval(period)) ){

		document.forms[1].period.focus();

		document.forms[1].period.select();

		alert("Invalid input");

		return false;

	}else{

		document.forms[1].period.value = period;

		return true;

	}

}

function changeReward(){

	document.forms[1].reward.value = reward;

}

function calc(){

	if ( !changeLoan() ){

		return;

	}

	if ( !changeInterestRate() ){

		return;

	}

	if ( !changePeriod() ){

		return;

	}

	if ( document.forms[1].pmethod[0].checked ){

		ratio = 1.0 / 12.0;

		times = 12 * period;

	}else{

		ratio = 14.0 / 365.0;

		//times = 24 * period;
		times = 26 * period;

	}

	result = loan;

	result *= interestRate * ratio / 100;

	result *= Math.pow((1.0 + interestRate / 100 * ratio),times);

	result /= Math.pow((1.0 + interestRate / 100 * ratio),times) - 1.0;

	document.forms[1].reward.value = formatMoney(Math.round(result * 100) / 100);

}