<?php
$start = strtotime('2014-09-01');
$end = strtotime('2014-10-01');
$stamp = $start;
$months = array();
do {
$next_stamp = mktime(0,0,0, date('n',$stamp)+1, 1, date('Y',$stamp));
$next_stamp = min($next_stamp, $end);
$months[] = min((ceil($next_stamp/3600/24)-floor($stamp/3600/24))/date('t', $stamp), 1);
$stamp = $next_stamp;
} while ($stamp < $end);
var_dump($months);
preferences:
38.58 ms | 402 KiB | 5 Q