/*--------------------------
Fuel Cost Calculator
---------------------------*/

function Calculation()
	{
	var error_flag = false;
	var error_string = "";
	
	if (isNaN(document.calcfuel.mileage.value))
		{
		error_flag = true
		error_string = error_string + "Non numeric mileage.\n"
		}
	
	if (isNaN(document.calcfuel.mpg.value))
		{
		error_flag = true
		error_string = error_string + "Non numeric miles per gallon.\n"
		}
		
	if (isNaN(document.calcfuel.fuelprice.value))
		{
		error_flag = true
		error_string = error_string + "Non numeric fuel price.\n"
		}
		
	if (error_flag)
		alert(error_string);
	else
		{
		var fuelcost = ((document.calcfuel.mileage.value / document.calcfuel.mpg.value) * 4.54 * document.calcfuel.fuelprice.value) / 100;
		fuelcost = (parseInt(fuelcost * 100)) / 100;
		
		var smarter = (fuelcost - ((fuelcost / 100) * 8) );
		smarter = (parseInt(smarter * 100)) / 100;
		
		var savings = ((fuelcost / 100) * 8 );
		savings = (parseInt(savings * 100)) / 100;
		
		if (isNaN(fuelcost))
			{
			error_string = "Incorrect data entered\n";
			alert(error_string);
			}
		else
			{
			document.calcfuel.output_value.value=roundVal(fuelcost);
			document.calcfuel.smarter.value=roundVal(smarter);
			document.calcfuel.savings.value=roundVal(savings);
			
			//return false;
			}
		}
	}
	
function roundVal(n) {
  var s = "" + Math.round(n * 100) / 100
  var i = s.indexOf('.')
  if (i < 0) return s + ".00"
  var t = s.substring(0, i + 1) + s.substring(i + 1, i + 3)
  if (i + 2 == s.length) t += "0"
  return t
}