function blockerror()
		{  return true;  	}
	window.onerror = blockerror;
	function floor(number)
		{	return Math.floor(number*Math.pow(10,2))/Math.pow(10,2);	}
	function dosum()
		{
		var mi = document.Calculator.IR.value / 1200;
		var base = 1;
		var mbase = 1 + mi;
		for (i=0; i<document.Calculator.YR.value * 12; i++)
			{	base = base * mbase	}
		document.Calculator.PI.value = floor(document.Calculator.LA.value * mi / ( 1 - (1/base)))
		document.Calculator.MT.value = floor(document.Calculator.AT.value / 12)
		document.Calculator.MI.value = floor(document.Calculator.AI.value / 12)
		var dasum = document.Calculator.LA.value * mi / ( 1 - (1/base)) +
					 document.Calculator.AT.value / 12 + document.Calculator.AI.value / 12;
		document.Calculator.MP.value = floor(dasum);
		}