Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Calculation/Engineering.php
public static function ERFC($x)
    {
        $x = Functions::flattenSingleValue($x);

        if (is_numeric($x)) {
            return self::erfcVal($x);
        }

        return Functions::VALUE();
    }
public static function ERFC($x)
    {
        $x = Functions::flattenSingleValue($x);

        if (is_numeric($x)) {
            return self::erfcVal($x);
        }

        return Functions::VALUE();
    }
ERFC.

Returns the complementary ERF function integrated between x and infinity

Note: In Excel 2007 or earlier, if you input a negative value for the lower bound argument,
the function would return a #NUM! error. However, in Excel 2010, the function algorithm was
improved, so that it can now calculate the function for both positive and negative x values.
PhpSpreadsheet follows Excel 2010 behaviour, and accepts nagative arguments.

Excel Function:
ERFC(x)

@param float $x The lower bound for integrating ERFC

@return float