#35986 [Opn->Bgs]: Rounding error
| From: | tony2001@php.net | Date: | Thu, 12 Jan 2006 21:47:16 +0000 |
| Subject: | #35986 [Opn->Bgs]: Rounding error | ||
| References: | 1 | Groups: | php.bugs |
| Request: | Send a blank email to php-bugs+get-91814@lists.php.net to get a copy of this message | ||
ID: 35986
Updated by: tony2001@php.net
Reported By: nathan at pngwyn dot com
-Status: Open
+Status: Bogus
Bug Type: *Math Functions
Operating System: Linux
PHP Version: 5.1.2
New Comment:
Floating point values have a limited precision. Hence a value might
not have the same string representation after any processing. That also
includes writing a floating point value in your script and directly
printing it without any mathematical operations.
If you would like to know more about "floats" and what IEEE
754 is read this:
http://docs.sun.com/source/806-3568/ncg_goldberg.html
Thank you for your interest in PHP.
Previous Comments:
------------------------------------------------------------------------
[2006-01-12 22:37:48] nathan at pngwyn dot com
Description:
------------
Rounding error on all numbers between 2048 and 8191 ending with .575 -
When rounding to two decimal places.
For Example, instead of rounding 2048.575 up to 2048.58 it is rounding
down to 2048.57
See attached Code.
Example URL: http://www.pngwyn.com/test.php
* Note: Example URL is running 5.05 - But this has been tested on 5.1.2
as well.
Reproduce code:
---------------
<?php
$start = 2040.575;
$for = '6500';
$max = $for + $start;
print("<font face=verdana size=2><a
href=\"http://www.pngwyn.com/phpinfo.php\">PHP
Info for this
Server</a><br><br>");
for($i = $start; $i <= $max; $i++) {
$round = round($i, 2);
print("Original Number: <b>$i</b> --- Rounded Number:
<b>$round</b> <br>");
}
?>
Expected result:
----------------
Original Number: 2046.575 --- Rounded Number: 2046.58
Original Number: 2047.575 --- Rounded Number: 2047.58
Original Number: 2048.575 --- Rounded Number: 2048.58
Original Number: 2049.575 --- Rounded Number: 2049.58
[ 2050.575 - 8189.575 ... ]
Original Number: 8190.575 --- Rounded Number: 8190.58
Original Number: 8191.575 --- Rounded Number: 8191.58
Original Number: 8192.575 --- Rounded Number: 8192.58
Original Number: 8193.575 --- Rounded Number: 8193.58
Actual result:
--------------
Original Number: 2046.575 --- Rounded Number: 2046.58
Original Number: 2047.575 --- Rounded Number: 2047.58
Original Number: 2048.575 --- Rounded Number: 2048.57
Original Number: 2049.575 --- Rounded Number: 2049.57
[ 2050.575 - 8189.575 ... ]
Original Number: 8190.575 --- Rounded Number: 8190.57
Original Number: 8191.575 --- Rounded Number: 8191.57
Original Number: 8192.575 --- Rounded Number: 8192.58
Original Number: 8193.575 --- Rounded Number: 8193.58
------------------------------------------------------------------------
--
Edit this bug report at http://bugs.php.net/?id=35986&edit=1