<?php
declare(strict_types=1);

$a = imageaffinematrixget(IMG_AFFINE_TRANSLATE, ["x" => 2.0, "y" => 1.0]);
$b = imageaffinematrixget(IMG_AFFINE_TRANSLATE, ["x" => 3.0, "y" => 4.0]);
echo implode(",", imageaffinematrixconcat($a, $b)), "\n";