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Subject: [PHP-DEV] Proposal for `BcMath\Number::sum()`, `max()`, and `min()`
Message-ID: <E9562258-2983-4A12-925A-A811D7703B6F@sakiot.com>
Date: Sun, 15 Jun 2025 18:07:31 +0900
To: PHP internals <internals@lists.php.net>
From: saki@sakiot.com (Saki Takamachi)

Hi internals!

I would like to propose adding three static methods =E2=80=94 `sum()`, =
`max()`, and `min()` =E2=80=94 to BcMath\Number.
Before moving forward, I=E2=80=99d like to gauge whether there is =
general interest or demand for such functionality.

Of course, I'm aware that these operations can be implemented easily in =
userland code. However, having them as built-in methods provides a clear =
performance advantage.

In a quick benchmark using a prototype implementation, I observed that =
`sum()` was approximately 5x faster than a userland implementation, =
while `max()` and `min()` were roughly 2x faster.

I also experimented with an `avg()` method, but found that the =
performance difference between built-in and userland implementations was =
negligible. For that reason, I'm not including it in this proposal.

The proposed method signatures are as follows:
```
public static function sum(array $nums, ?int $scale =3D null): Number {}
public static function max(array $nums, ?int $scale =3D null): Number {}
public static function min(array $nums, ?int $scale =3D null): Number {}
```

Each element in `$nums` should be of type `Number`, `string`, or `int`.

For reference, here are the userland implementations I used for =
comparison:

sum:
```
$nums =3D [/* omit */];
$num_0 =3D new BcMath\Number(0);
foreach ($nums as $num) {
   $num_0 +=3D $num;
}
```

max (and min with slight modification):
```
$nums =3D [/* omit */];
$num_0 =3D array_shift($nums);
foreach ($nums as $num) {
   $num_0 =3D $num_0 >=3D $num ? $num_0 : $num;
}
```

Regards,

Saki=