php - 評価のための ELO アルゴリズムの実装

Question

こんにちは、私は elo アルゴリズムを実装して、LAN 内のプレイヤーを評価したいと考えていました。私のphpスクリプトには以下が含まれています。

<?php
class Rating
{
    const KFACTOR = 16;
    protected $_ratingA;
    protected $_ratingB;
    protected $_scoreA;
    protected $_scoreB;
    protected $_expectedA;
    protected $_expectedB;
    protected $_newRatingA;
    protected $_newRatingB;
    public function  __construct($ratingA,$ratingB,$scoreA,$scoreB)
    {
        $this->_ratingA = $ratingA;
        $this->_ratingB = $ratingB;
        $this->_scoreA = $scoreA;
        $this->_scoreB = $scoreB;
        $expectedScores = $this -> _getExpectedScores($this -> _ratingA,$this -> _ratingB);
        $this->_expectedA = $expectedScores['a'];
        $this->_expectedB = $expectedScores['b'];
        $newRatings = $this ->_getNewRatings($this -> _ratingA, $this -> _ratingB, $this -> _expectedA, $this -> _expectedB, $this -> _scoreA, $this -> _scoreB);
        $this->_newRatingA = $newRatings['a'];
        $this->_newRatingB = $newRatings['b'];
    }
    public function setNewSettings($ratingA,$ratingB,$scoreA,$scoreB)
    {
        $this -> _ratingA = $ratingA;
        $this -> _ratingB = $ratingB;
        $this -> _scoreA = $scoreA;
        $this -> _scoreB = $scoreB;
        $expectedScores = $this -> _getExpectedScores($this -> _ratingA,$this -> _ratingB);
        $this -> _expectedA = $expectedScores['a'];
        $this -> _expectedB = $expectedScores['b'];
        $newRatings = $this ->_getNewRatings($this -> _ratingA, $this -> _ratingB, $this -> _expectedA, $this -> _expectedB, $this -> _scoreA, $this -> _scoreB);
        $this -> _newRatingA = $newRatings['a'];
        $this -> _newRatingB = $newRatings['b'];
    }
    public function getNewRatings()
    {
        return array (
            'a' => $this -> _newRatingA,
            'b' => $this -> _newRatingB
        );
    }
    protected function _getExpectedScores($ratingA,$ratingB)
    {
        $expectedScoreA = 1 / ( 1 + ( pow( 10 , ( $ratingB - $ratingA ) / 400 ) ) );
        $expectedScoreB = 1 / ( 1 + ( pow( 10 , ( $ratingA - $ratingB ) / 400 ) ) );
        return array (
            'a' => $expectedScoreA,
            'b' => $expectedScoreB
        );
    }
    protected function _getNewRatings($ratingA,$ratingB,$expectedA,$expectedB,$scoreA,$scoreB)
    {
        $newRatingA = $ratingA + ( self::KFACTOR * ( $scoreA - $expectedA ) );
        $newRatingB = $ratingB + ( self::KFACTOR * ( $scoreB - $expectedB ) );
        return array (
            'a' => $newRatingA,
            'b' => $newRatingB
        );
    }
}
//first player won
$first_player_rating=200;
$second_player_rating=200;
$n=new Rating($first_pic_rating,$second_pic_rating,1400,1400);
$a=$n->getNewRatings();
var_dump($a);
?>

私は first_player_rating と second_player_rating の両方に 200 を与えましたが、これは間違っていますが、問題は、最初のプレイヤーが試合に勝ったばかりの場合、first_player_rating と second_player_rating の値はどれくらいであるべきかということです...