Get Extremes of integer array

extremes.php

<?php

function getExtremes($test)
{
    $sum = array_sum($test);
    $average = $sum / count($test);
    $deviations = array();
    $ret = array();

    for ($i = 0; $i < count($test); $i++) 
    {
        $deviation = $test[$i] - $average;
        $deviation = abs($deviation);
        $deviations[$i] = $deviation;
    }

    // Extreme value
    $max = max($deviations);

    foreach ($deviations as $deviation) 
    {
        if ($deviation == $max) {
            $ret[] = $deviation;
        }
    }

    if (count($ret) == 1) {
        $ret = $ret[0];
    }

    var_dump($ret);
}

// Set of arrays to test
$tests = array(
    array( 1,2,3,4,5,6,7,8,89,9,0,45,3,-1,-1234,-1234,234,1234,1234, -234, 345, -345 ),
    array( 1,2,3,4,5,6,7,8,89,9,0,45,3,-1,-1234),
);  

// Loop the arrays to test each of them
foreach ($tests as $test) 
{
    getExtremes($test);
}