- pow: documentation ( source)
<?php
class Ratings {
const K = 32;
private $rating1;
private $rating2;
public function __construct($rating1, $rating2) {
$this->rating1 = $rating1;
$this->rating2 = $rating2;
}
public function calculateChange() {
return 1 / (1 + pow(10, ($this->rating2 - $this->rating1) / 400)) * 100;
}
}
echo (new Ratings(4, 5))->calculateChange() . "%";