/**
* Get a Date object for the day before this one
*
* Get a Date object for the day before this one.
* The time of the returned Date object is the same as this time.
*
* @access public
* @return object Date Date representing the previous day
*/
function getPrevDay()
{
$day = Calc::prevDay($this->day, $this->month, $this->year, "%Y-%m-%d");
$date = sprintf("%s %02d:%02d:%02d", $day, $this->hour, $this->minute, $this->second);
$newDate = new Date();
$newDate->setDate($date);
return $newDate;
}