Multiply arrays

[Black_Knight]

What's the best way to multiply 2 arrays value by value in php?
E.g $a1 = array(1, 2, 3); $a2 = array(2, 4, 6);
Need $a3 to be (2, 8, 18).
I was hoping for a shortcut without using a for(each) loop.

Thanks

[NogDog]

First thing that comes to mind:

$keys = array_intersect_key($a1, $a2);
foreach($keys as $ix)
{
$a3[$ix] = $a1[$ix] * $a2[$ix];
}