how to get the date of last week's (tuesday or any other day) in php

$tuesday = strtotime('last Tuesday');
// check if we need to go back in time one more week
$tuesday = date('W', $tuesday)==date('W') ? $tuesday-7*86400 : $tuesday;

$tuesday = date('W', $tuesday)==date('W') ? $tuesday-7*86400+7200 : $tuesday;

echo strtotime('last Tuesday');

$z = date("Y-m-d", strtotime("last Saturday"));
$z = (date('W', strtotime($z)) == date('W')) ? (strtotime($z)-7*86400+7200) : strtotime($z);
print date("Y-m-d", $z);

// test: find last date for each day of the week
foreach (array('Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun') as $day) {
    print $day . " => " . date('m/d/Y', last_dayofweek($day)) . "n";
}

function last_dayofweek($day)
{
    // return timestamp of last Monday...Friday
    // will return today if today is the requested weekday
    $day = strtolower(substr($day, 0, 3));
    if (strtolower(date('D')) == $day)
        return strtotime("today");
    else
        return strtotime("last {$day}");
}