function calcpayment() {
	if((document.simpleinterestform.amount.value <= 0 )
		|| (document.simpleinterestform.interestrate.value <= 0)
		|| (document.simpleinterestform.term.value <= 0))
	{	return false;	}
   var amount = document.simpleinterestform.amount.value;
   var interestrate = document.simpleinterestform.interestrate.value / 1200;
   var term = document.simpleinterestform.term.value * 12;
   var monthlytaxes = document.simpleinterestform.taxes.value / 12;
   var monthlyinsurance = document.simpleinterestform.insurance.value / 12;
   var total=1;
   for (i=0;i<term;i++) {
      total = total * (1 + interestrate);
   }
   monthlypayment = amount * interestrate / ( 1 - (1/total));
   monthlypayment = monthlypayment + monthlytaxes + monthlyinsurance;
  var paymentvar = Math.round(monthlypayment*100)/100;
  document.simpleinterestform.payment.value = paymentvar.toFixed(2);
}