test3.php

<?php

function pc_permute($items, $perms = array( )) {
    if (empty($items)) { 
        $res = $perms[0] + 13.0 * $perms[1] / $perms[2] + $perms[3] + 12.0 * $perms[4] - $perms[5] - 11.0 + $perms[6] * $perms[7] / $perms[8] - 10.0;
        if ($res == 66.0) {
            print join(' ', $perms) . ": $res\n";
        }
    }  else {
        for ($i = count($items) - 1; $i >= 0; --$i) {
             $newitems = $items;
             $newperms = $perms;
             list($foo) = array_splice($newitems, $i, 1);
             array_unshift($newperms, $foo);
             pc_permute($newitems, $newperms);
         }
    }
}

$iv = [1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0];

pc_permute($iv);