function calculatebmi() 
{
	/*BMI= Weight(kg) / (Height x height) (m)*/
	var weight, height, bmi;
	weight = document.getElementById("bmiweight");
	height = document.getElementById("bmiheight");
	bmi = document.getElementById("bmibmi");
	if (weight.value)
	{
		if (isNaN(weight.value) || weight.value < 0 || weight.value > 600)
		{
			alert("Please enter a weight in kilograms (kg).");
			weight.focus();
		}
		else
		{
			if (height.value)
			{
				if(isNaN(height.value) || height.value < 0 || height.value > 3)
				{
					alert("Please enter a height in metres (m).");
					height.focus();
				}
				else
				{
					var floatbmi = new Number();
					var floatweight = new Number(weight.value);
					var floatheight = new Number(height.value);
					floatweight = floatweight.toFixed(2);
					floatheight = floatheight.toFixed(2);
					floatbmi = floatweight / (floatheight * floatheight);
					floatbmi = floatbmi.toFixed(2);
					/*floatbmi = format( weight.value / ( height.value * height.value ) , 1) ;*/
					bmi.value = floatbmi;
					window.open("RecordCalcResults.asp?ans=bmi&ans=" + floatweight + "&ans=" + floatheight + "&ans=" + floatbmi, "", "width=50,height=50");
				}
			}
			else
			{
				alert("Please enter a height in metres (m).");
				height.focus();
			}
		}
	}
	else
	{
		alert("Please enter a weight in kilograms (kg).");
		weight.focus();
	}
	return false;
}