fdiv

Subject: Compatibility for older PHP

Text: Equivalent for versions before 8.0. Handles the sign of zero for INF results.

<?php
if (!function_exists('fdiv')) {
    function fdiv(float $a, float $b): float
    {
        if (is_nan($a) || is_nan($b)) return NAN;
        if ($b != 0.0) return $a / $b;
        if ($a == 0.0) return NAN;

        $check = function ($v) {
            if ($v > 0) return 1;
            if ($v < 0) return -1;
            return pack('d', (float)$v) === pack('d', 0.0) ? 1 : -1;
        };

        return ($check($a) === $check($b)) ? INF : -INF;
    }
}
?>