function writetolayer(lay,txt) {
			
    var ie4 = (document.all) ? true : false;
    var ns4 = (document.layers) ? true : false;
    var ns6 = (document.getElementById && !document.all) ? true : false;

    if (ie4) {
        document.all[lay].innerHTML = txt;
    }
    if (ns4) {
        document[lay].document.write(txt);
        document[lay].document.close();
    }
    if (ns6) {
	    document.getElementById(lay).innerHTML = txt;
    }
}

function validateForm(){

	errormsg = "The following fields are required:\n";

	a = document.form1.years.value;
	b = document.form1.loanamount.value;
	c = document.form1.interest.value;

	if (a == ''){errormsg += "\n  - Please enter Period in years" + "\t\t";}
	if (b == ''){errormsg += "\n  - Please enter Loan amount" + "\t\t";}
	if (c == ''){errormsg += "\n  - Please enter Interest rate" + "\t\t";}

	
	if (errormsg != "The following fields are required:\n")
	{
		alert (errormsg);
		return false;
	}
	else 
	{
		return true;
	}
 
}

function doCalcs() {

	if (validateForm()) {

		var loanAmount, interestdividedby100, yearsLeft, interestEntered;
		var myvalue1, myvalue2, x, y, repayment, interestOnly;
		
		loanAmount = document.form1.loanamount.value;
		interestEntered = document.form1.interest.value;
		yearsLeft = document.form1.years.value;
		
		interestdividedby100 = interestEntered/100;
		
		myvalue1 = loanAmount*(interestdividedby100/12);
		
		x=(1+(interestdividedby100/12));
		y=((yearsLeft*12)*-1);
		
		myvalue2 = 1-Math.pow(x,y);
		

		RepaymentMessage = '£ ' + getRepayment(myvalue1, myvalue2);	
		InterestOnlyMessage = '£ ' + getInterest(interestdividedby100, loanAmount);

		writetolayer('repaymentmsg', RepaymentMessage);
		writetolayer('interestonlymsg', InterestOnlyMessage);
	
		return false;
	}

}

function getRepayment(value1, value2)
{
    return ((Math.round(100*value1/value2))/100).toFixed(2);
}

function getInterest(value1, value2)
{
    return ((Math.round(value1*value2))/12).toFixed(2);
}

function clearForm()
{
        document.form1.reset();
		writetolayer('repaymentmsg', ' ');
		writetolayer('interestonlymsg', ' ');
		
}

//-->