#28542 [Opn->Bgs]: Floating point error while adding values to a float var
| From: | derick@php.net | Date: | Thu, 27 May 2004 13:15:09 +0000 |
| Subject: | #28542 [Opn->Bgs]: Floating point error while adding values to a float var | ||
| References: | 1 | Groups: | php.bugs |
| Request: | Send a blank email to php-bugs+get-60071@lists.php.net to get a copy of this message | ||
ID: 28542
Updated by: derick@php.net
Reported By: tny at eyefi dot nl
-Status: Open
+Status: Bogus
Bug Type: Variables related
Operating System: Linix / BSDs
PHP Version: 4.3.6
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.
Thank you for your interest in PHP.
.
Previous Comments:
------------------------------------------------------------------------
[2004-05-27 15:01:29] tny at eyefi dot nl
Description:
------------
When adding a float value to a variable (starting with a negative
value) in a loop the result that should be zero (0) is nearly zero, but
not exact zero.
Reproduce code:
---------------
<?php
for ($i = -1.0; $i <= 1.0; $i += 0.1) {
echo $i . "\n";
}
?>
Expected result:
----------------
-1
-0.9
-0.8
-0.7
-0.6
-0.5
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Actual result:
--------------
-1
-0.9
-0.8
-0.7
-0.6
-0.5
-0.4
-0.3
-0.2
-0.1
-1.38777878078E-16
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
------------------------------------------------------------------------
--
Edit this bug report at http://bugs.php.net/?id=28542&edit=1