PHP で、月曜日から始まる特定の週番号内の曜日を抽出するにはどうすればよいですか?

<code class="php">$week_number = 40;
$year = 2008;
for ($day = 1; $day <= 7; $day++) {
    printf('%s\n', date('m/d/Y', strtotime($year . "W" . $week_number . $day)));
}

10/06/2008
10/07/2008
10/08/2008
10/09/2008
10/10/2008
10/11/2008
10/12/2008

<code class="php">function week_from_monday($date) {
    list($day, $month, $year) = explode('-', $date);

    $wkday = date('l', mktime('0', '0', '0', $month, $day, $year));

    switch ($wkday) {
        case 'Monday': $numDaysToMon = 0; break;
        case 'Tuesday': $numDaysToMon = 1; break;
        case 'Wednesday': $numDaysToMon = 2; break;
        case 'Thursday': $numDaysToMon = 3; break;
        case 'Friday': $numDaysToMon = 4; break;
        case 'Saturday': $numDaysToMon = 5; break;
        case 'Sunday': $numDaysToMon = 6; break;
    }

    $monday = mktime('0', '0', '0', $month, $day - $numDaysToMon, $year);

    $seconds_in_a_day = 86400;

    for ($i = 0; $i < 7; $i++) {
        $dates[$i] = date('Y-m-d', $monday + ($seconds_in_a_day * $i));
    }

    return $dates;
}

Array
(
    [0] => 2008-10-06
    [1] => 2008-10-07
    [2] => 2008-10-08
    [3] => 2008-10-09
    [4] => 2008-10-10
    [5] => 2008-10-11
    [6] => 2008-10-12
)</code>