How not to format dates

public function dummyEachWeekMonSunRows($StartDate, $EndDate) {
        $StartDate = strtotime($StartDate);
        $EndDate = strtotime($EndDate);
        $week_data = array();
        $chart_data = array();
        $nav_date = $StartDate;
        $end_date = $EndDate;
        $partial_range_start = "";
        $partial_range_end = "";
        $nav_date = strtotime("next Monday", strtotime("-7 days", $nav_date));
        if (date('mdY', $StartDate) != date('mdY', $nav_date)) {
            $partial_range_start = " (Partial Week)";
        }
        $nav_week_end = $nav_date;
        $nav_week_end = strtotime('+6 days', $nav_week_end);
        $end_date = strtotime("next Sunday", strtotime('-7 days', $end_date));
        if (date('mdY', $EndDate) != date('mdY', $end_date)) {
            if (($EndDate - $StartDate) / (24 * 60 * 60) > 7) {
                $partial_range_end = " (Partial Week)";
            } else {
                if ($partial_range_start == "") {
                    $partial_range_end = " (Partial Week)";
                }
            }
        }
        while ($EndDate >= $nav_date) {
            $nav = date('Y-W', $nav_date);
            $nav_week_end = $nav_date;
            $nav_week_start = $nav_date;
            $nav_week_end = strtotime('+6 days', $nav_week_end);
            //check partial end date
            if ($nav_week_end >= $EndDate) {
                $nav_week_end = $EndDate;
            }
            if ($partial_range_start != "") {
                $nav_range = $this->common->date($StartDate, 'SHORT') . " - " . $this->common->date($nav_week_end, 'SHORT') /* . $partial_range_start */;
            } else {
                $nav_range = $this->common->date($nav_date, 'SHORT') . " - " . $this->common->date($nav_week_end, 'SHORT');
            }
            $partial_range_start = "";
            $week_data[$nav] = (string)$nav_range;
            $nav_date = strtotime('next Monday', $nav_date);
        }
        if ($partial_range_end != "") {
            $week_data[$nav] = (string)$nav_range /* . " " . $partial_range_end */;
        }
        return $week_data;
    }