function changeUnits(unit)
{
	document.getElementById("lblAnswer").innerHTML = "0.00";
	document.getElementById("lblAnswer2").innerHTML = "0.00";
	
	if (unit == "standard")
	{
		// labels
		document.getElementById("lblRollWeightUnit").innerHTML = "lbs";
		document.getElementById("lblWebWidthUnit").innerHTML = "inches";
		document.getElementById("lblWebCaliperUnit").innerHTML = "inches";
		document.getElementById("lblRollLengthUnit").innerHTML = "feet";
		document.getElementById("lblCODUnit").innerHTML = "inches";
		document.getElementById("lblRollDiameterUnit").innerHTML = "inches";
		document.getElementById("lblAnswerUnit").innerHTML = "lbs/in<sup>3</sup>";
		document.getElementById("lblAnswerUnit2").innerHTML = "lbs/in<sup>3</sup>";
		
		// values
		document.getElementById("txtRollWeight").value = convert('kilosToPounds', document.getElementById("txtRollWeight").value, 3);
		document.getElementById("txtWebWidth").value = convert('metersToInches', document.getElementById("txtWebWidth").value, 3);
		document.getElementById("txtWebCaliper").value = convert('micronsToInches', document.getElementById("txtWebCaliper").value, 4);
		document.getElementById("txtRollLength").value = convert('metersToFeet', document.getElementById("txtRollLength").value, 2);
		document.getElementById("txtCOD").value = convert('millimetersToInches', document.getElementById("txtCOD").value, 3);
		document.getElementById("txtRollDiameter").value = convert('millimetersToInches', document.getElementById("txtRollDiameter").value, 3);
		
	}
	else
	{
		// labels
		document.getElementById("lblRollWeightUnit").innerHTML = "kg";
		document.getElementById("lblWebWidthUnit").innerHTML = "meters";
		document.getElementById("lblWebCaliperUnit").innerHTML = "microns";
		document.getElementById("lblRollLengthUnit").innerHTML = "meters";
		document.getElementById("lblCODUnit").innerHTML = "millimeters";
		document.getElementById("lblRollDiameterUnit").innerHTML = "millimeters";
		document.getElementById("lblAnswerUnit").innerHTML = "g/cm<sup>3</sup>";
		document.getElementById("lblAnswerUnit2").innerHTML = "g/cm<sup>3</sup>";
		
		// values
		document.getElementById("txtRollWeight").value = convert('poundsToKilos', document.getElementById("txtRollWeight").value, 3);
		document.getElementById("txtWebWidth").value = convert('inchesToMeters', document.getElementById("txtWebWidth").value, 3);
		document.getElementById("txtWebCaliper").value = convert('inchesToMicrons', document.getElementById("txtWebCaliper").value, 4);
		document.getElementById("txtRollLength").value = convert('feetToMeters', document.getElementById("txtRollLength").value, 3);
		document.getElementById("txtCOD").value = convert('inchesToMillimeters', document.getElementById("txtCOD").value, 3);
		document.getElementById("txtRollDiameter").value = convert('inchesToMillimeters', document.getElementById("txtRollDiameter").value, 3);
		
	}
}


function calculate(method)
{
	var length, core, caliper, weight, diameter, answer, width, multiplier, divisor;
	var measure;
	var answerLabel;
	
	if (document.frmMain.rdoMeasurement[0].checked)
	{
		measure = document.frmMain.rdoMeasurement[0].value.toLowerCase();
	}
	else
	{
		measure = document.frmMain.rdoMeasurement[1].value.toLowerCase();
	}
		
	length = document.getElementById("txtRollLength").value;
	width = document.getElementById("txtWebWidth").value;
	core = document.getElementById("txtCOD").value;
	caliper = document.getElementById("txtWebCaliper").value;
	weight = document.getElementById("txtRollWeight").value;
	diameter = document.getElementById("txtRollDiameter").value;
	
	// for the standard measure, the formulas take a multiplier of 12, so we set that here if needed
	multiplier = 1; // metric
	if (measure == 'standard')
	{
		multiplier = 12; // standard
		divisor = 1;
	}
	else
    {
        multiplier = 1; // metric
        divisor = 1000;
    }
	
	if (method == 1)
	{
		answer = (weight / (width * caliper * length * multiplier)) * divisor;
		
		answerLabel = "lblAnswer";
	}
	else
	{
		answer = (weight / (Math.PI / 4 * ((diameter * diameter) - (core * core)) * width)) * divisor;
		answerLabel = "lblAnswer2";
	}
	
	answer = roundIt(answer, 3);
	
	document.getElementById(answerLabel).innerHTML = answer;
}