code: function _fnConvertToWidth ( sWidth, nParent )
  		{
  			if ( !sWidth || sWidth === null || sWidth === '' )
  			{
  				return 0;
  			}
  			
  			if ( !nParent )
  			{
  				nParent = document.getElementsByTagName('body')[0];
  			}
  			
  			var iWidth;
  			var nTmp = document.createElement( "div" );
  			nTmp.style.width = _fnStringToCss( sWidth );
  			
  			nParent.appendChild( nTmp );
  			iWidth = nTmp.offsetWidth;
  			nParent.removeChild( nTmp );
  			
  			return ( iWidth );
  		}
docs: Convert a CSS unit width to pixels (e.g. 2em)
  @param {string} sWidth width to be converted
  @param {node} nParent parent to get the with for (required for relative widths) - optional
  @returns {int} iWidth width in pixels
  @memberof DataTable#oApi