static function _getInsidersCombinations(&$insiders, $size, $pos = 0)
{
if ($size <= 0) {
return array(1);
}
$return = array();
$end = count($insiders) - $size;
for ($i = $pos; $i <= $end; $i++) {
$subtree = Approximation::_getInsidersCombinations($insiders, $size - 1, $i + 1);
foreach ($subtree as $value) {
$return[] = $insiders[$i] * $value;
}
}
return $return;
}
