PHP5.2.17在計算小數時的有關問題

PHP5.2.17在計算小數時的問題，求救
$v['closed_price'] = 15.05;
$v['f_forecast_price'] = 14.68;
$diff = floatval($v['closed_price'] - $v['f_forecast_price']);
$closed_1 = floatval($v['closed_price']) * 0.1;
$rate = ($closed_1 - $dff) / $closed_1 ;

var_dump($closed_1 - $dff, $diff, $rate);


為什麼$closed_1 - $dff是對的，但($closed_1 - $dff) / $closed_1得到一個1呢？？

理論上應該是小數才對。

為啥呢？？？

------解決方案--------------------
太不仔細了

$diff = floatval($v['closed_price'] - $v['f_forecast_price']);
$closed_1 = floatval($v['closed_price']) * 0.1;
$rate = ($closed_1 - $dff) / $closed_1 ;

var_dump($closed_1 - $dff, $diff, $rate);

