<?php

// Calculate the expected % outcome

function expected($Rb, $Ra) {

 return 1/(1 + pow(10, ($Rb-$Ra)/400));

}

// Calculate the new winnner score

function win($score, $expected, $k = 24) {

 return $score + $k * (1-$expected);

}

// Calculate the new loser score

function loss($score, $expected, $k = 24) {

 return $score + $k * (0-$expected);

}

?>