Calculate date from ISO 8601 week number

gistfile1.aw

<?php

function get_week_number_date($week, $year)
{

	// Count from '0104' because January 4th is always in week 1
	// (according to ISO 8601).
	$time = strtotime($year . '0104 +' . ($weekNumber - 1) . ' weeks');
	
	// Get the time of the first day of the week
	return strtotime('-' . (date('w', $time) - 1) . ' days', $time);

}

get_week_number_date(14, 2012);