function retrieveHeight(id){
	
	var clientObj =document.getElementById(id);

	var clientObjHeightNumber;
	
	if (window.getComputedStyle) 
	{		
		var  CSClientObj = document.defaultView.getComputedStyle(clientObj,'');
		var clientObjHeight = CSClientObj.getPropertyValue('height');
		clientObjHeightNumber = clientObjHeight.substring(0,clientObjHeight.length-2);
	}
	else if (clientObj.currentStyle) 	
	{
		clientObjHeightNumber = eval('clientObj.offsetHeight');
	}
	return clientObjHeightNumber;
}	
function retrieveWidth(id){
	
	var clientObj =document.getElementById(id);

	var clientObjWidthNumber;
	
	if (window.getComputedStyle) 
	{		
		var  CSClientObj = document.defaultView.getComputedStyle(clientObj,'');
		var clientObjWidth = CSClientObj.getPropertyValue('width');
		clientObjWidthNumber = clientObjWidth.substring(0,clientObjWidth.length-2);
	}
	else if (clientObj.currentStyle) 	
	{
		clientObjWidthNumber = eval('clientObj.offsetWidth');
	}
	return clientObjWidthNumber;
}	

function computeWindowWidth()
{
	var w = 0;

	//IE
	if(!window.innerWidth)
	{
		//strict mode
		if(!(document.documentElement.clientWidth == 0))
		{
			w = document.documentElement.clientWidth;
		}
		//quirks mode
		else
		{
			w = document.body.clientWidth;
		}
	}
	//w3c
	else
	{
		w = window.innerWidth;
	}
	return w;
}

function computeWindowHeight()
{
	var h = 0;

	//IE
	if(!window.innerWidth)
	{
		//strict mode
		if(!(document.documentElement.clientWidth == 0))
		{
			h = document.documentElement.clientHeight;
		}
		//quirks mode
		else
		{
			h = document.body.clientHeight;
		}
	}
	//w3c
	else
	{
		h = window.innerHeight;
	}
	return h;
}

function centerElement(id)
{
	var windowWidth = computeWindowWidth();
	var windowHeigth = computeWindowHeight();
	
	var divWidth = retrieveWidth(id);
	var divHeight = retrieveHeight(id);
	
	var leftCoord = String(new Number(windowWidth/2) - new Number(divWidth/2));
	
	var div =document.getElementById(id);
	div.style.left= leftCoord +"px";
}