function calculate_time_zone() {

   var rightNow = new Date();

   var jan1 = new Date(rightNow.getFullYear(), 0, 1, 0, 0, 0, 0);  // jan 1st

   var june1 = new Date(rightNow.getFullYear(), 6, 1, 0, 0, 0, 0); // june 1st

   var temp = jan1.toGMTString();

   var jan2 = new Date(temp.substring(0, temp.lastIndexOf(" ")-1));

   temp = june1.toGMTString();

   var june2 = new Date(temp.substring(0, temp.lastIndexOf(" ")-1));

   var std_time_offset = (jan1 - jan2) / (1000 * 60 * 60);

   var daylight_time_offset = (june1 - june2) / (1000 * 60 * 60);

   var dst;

   if (std_time_offset == daylight_time_offset) {

		dst = "0"; // daylight savings time is NOT observed

   } else {

   		// positive is southern, negative is northern hemisphere

		var hemisphere = std_time_offset - daylight_time_offset;

		if (hemisphere >= 0)

			std_time_offset = daylight_time_offset;

		dst = "1"; // daylight savings time is observed

   }

   setCookie('time_zone_client',convert(std_time_offset)+","+dst,365);

   

}



function convert(value) {

	var hours = parseInt(value);

   	value -= parseInt(value);

	value *= 60;

	var mins = parseInt(value);

   	value -= parseInt(value);

	value *= 60;

	var secs = parseInt(value);

	var display_hours = hours;

	display_hours = (hours < 10 && hours > 0) ? "+0"+hours : "+"+hours; // positive

	display_hours = (hours == 0) ? "0"+hours : display_hours; // handle GMT case (00:00)

	display_hours = (hours < 0 && hours > -10) ? "-0"+Math.abs(hours) : display_hours; // neg

    mins = (mins < 10) ? "0"+mins : mins;

	return display_hours+":"+mins;

}


function setCookie(c_name,value,expiredays)
{
      var exdate=new Date();
      exdate.setDate(exdate.getDate()+expiredays);
      document.cookie=c_name+ "=" +escape(value)+((expiredays==null) ? "" : ";expires="+exdate.toGMTString());
} 


onload = calculate_time_zone;