gcd_lcm.php

<?php
// Greatest Common Divisor and Least Common Multiple
function lcm_arr($items){
    // Input: An Array of numbers
    // Output: The LCM of the numbers

    while(2 <= count($items)){
        array_push($items, lcm(array_shift($items), array_shift($items)));
    }

    return reset($items);
}

function gcd($n, $m) {
    $n = abs($n); 
    $m = abs($m);
    if ($n==0 and $m==0)
        return 1; //avoid infinite recursion

    if ($n==$m and $n>=1)
        return $n;

    return $m<$n?gcd($n-$m,$n):gcd($n,$m-$n);
}

function lcm($n, $m) {
    return $m * ($n/gcd($n,$m));
}