function runCalc(){
			la = IsNumeric(document.getElementById("loanAmount").value) ? document.getElementById("loanAmount").value : 0;
			ir = IsNumeric(document.getElementById("interestRate").value) ?  document.getElementById("interestRate").value : 0;
			py = IsNumeric(document.getElementById("periodYears").value) ? document.getElementById("periodYears").value : 0;
			if (la > 0 && ir > 0 && py > 0){
				document.getElementById("repay-weekly").value = calcForPeriod(la,py,ir,52);
				document.getElementById("repay-firtnightly").value = calcForPeriod(la,py,ir,26);
				document.getElementById("repay-yearly").value = calcForPeriod(la,py,ir,12);
			}
		}
		
		function calcForPeriod(principal, period, rate, itterationsPerYear){
			var term = itterationsPerYear;
			var r = rate / 100 / term;
			var repay = ((principal*r)/(1-(1/Math.pow(1+r,(period * term)))));
				return CurrencyFormatted(repay);
		}
		
		function IsNumeric(sText){
		   var ValidChars = "0123456789.";
		   var IsNumber=true;
		   var Char;
		   for (i = 0; i < sText.length && IsNumber == true; i++) 
			  { 
			  Char = sText.charAt(i); 
			  if (ValidChars.indexOf(Char) == -1) 
				 {
				 IsNumber = false;
				 }
			  }
		   return IsNumber;   
		}
		
		function CurrencyFormatted(amount)
		{
			var i = parseFloat(amount);
			if(isNaN(i)) { i = 0.00; }
			var minus = '';
			if(i < 0) { minus = '-'; }
			i = Math.abs(i);
			i = parseInt((i + .005) * 100);
			i = i / 100;
			s = new String(i);
			if(s.indexOf('.') < 0) { s += '.00'; }
			if(s.indexOf('.') == (s.length - 2)) { s += '0'; }
			s = minus + s;
			return s;
		}