- abs: documentation ( source)
- str_repeat: documentation ( source)
- ceil: documentation ( source)
<?php
$size = 9;
$center = ceil($size/2);
$maxPost = abs($center - $size);
for ($i=0; $i<$size; $i++) {
$post = abs($center + $i - $size);
$pre = $maxPost - $post;
echo str_repeat(" ",$pre);
echo "x ";
echo str_repeat(" ", $post);
echo "\n";
}