php浮点运算和BCMath函数

$n = 2074.11;
$a = $n * 1000;
$r1 = $a == 2074110;
var_dump($r1);
$r2 = bccomp($a, 2074110);
var_dump($r2);
$b = bcmul($n, 1000);
$r3 = $b == 2074110;
var_dump($r3);