function cal()
{
	form = document.forms[0];
	var p = form.P.value;
	var i = form.I.value;
	var y = form.Y.value;
	var dp = form.DP.value;
	var amt = p - dp;
	form.M.value = amt;
	var r = i/(1200);
	var pmt = amt*(r/(1-(Math.pow((1+r),(-12*y)))));
	if(isNaN(pmt))
		form.Pymt.value='Error';
	else
		form.Pymt.value=Math.round(pmt*100)/100;
}