Hmmm...
Tested on my lappy, AMD Turion64 X2, Ubuntu Lucid Lynx 64-bit.
OpenOffice Calc:
Input: =161001.165-100000.009-60000.7-1000.456
Output: 0.00000000000557065504835919
Input: =161001.165+(-100000.009-60000.7-1000.456)
Output: 0
Input: =((161001.165-100000.009)-60000.7)-1000.456
Output: 0.00000000000557065504835919
MySQL:
mysql>
mysql> CREATE TABLE `sumtest` (
->
-> `numbers` double NOT NULL,
->
-> `group` varchar(3) NOT NULL DEFAULT 'all'
->
-> );
Query OK, 0 rows affected (0.14 sec)
mysql>
mysql>
mysql>
mysql> INSERT INTO `sumtest` (`numbers`, `group`) VALUES
->
-> (161001.165, 'all'),
->
-> (-100000.009, 'all'),
->
-> (-60000.7, 'all'),
->
-> (-1000.456, 'all');
Query OK, 4 rows affected (0.10 sec)
Records: 4 Duplicates: 0 Warnings: 0
mysql>
mysql>
mysql>
mysql> SELECT SUM( `numbers` )
->
-> FROM `sumtest`
->
-> WHERE `group` = 'all'
->
-> GROUP BY `group`;
+----------------------+
| SUM( `numbers` ) |
+----------------------+
| 5.57065504835919e-12 |
+----------------------+
1 row in set (0.04 sec)
2010/9/5 Raja Iskandar Shah <[email protected]>
> cool ;-)
>
> i wonder if the bug is identical across all 32bit and 64bit cpu ? or intel
> treats them differently than amd, than sunsparc, than arm ?
>
>
>
> On Sun, Sep 5, 2010 at 10:55 AM, Walter Heck - OlinData.com <
> [email protected]> wrote:
>
>> Usually the programming languages used for those kind of programs have
>> their own datatypes for ultra-high precision floating points. A 32 or
>> 64 bit datatype is not enough for them anyway. They use all kinds of
>> tricks/smart-assing to get around floating point rounding errors.
>>
>> Walter
>>
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