//Copyright © 2002 - 2010 PracticeWEB Ltd
/*--------------------------
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;
		
		if (isNaN(fuelcost))
			{
			error_string = "Incorrect data entered\n";
			alert(error_string);
			}
		else
			{
			document.calcfuel.output_value.value=fuelcost;
			return false;
			}
		}
	}