function dateChanged(calendar) {
    // Beware that this function is called even if the end-user only
    // changed the month/year.  In order to determine if a date was
    // clicked you can use the dateClicked property of the calendar:
    if (calendar.dateClicked) {
      var y = calendar.date.getFullYear();
      var m = calendar.date.getMonth()+1;// integer, 0..11
      var d = calendar.date.getDate(); // integer, 1..31
      window.location =  m + "_" + d ;
    }
  };