Bug #64543 [Opn->Nab]: Incorrect result of round

From: Date: Thu, 28 Mar 2013 17:00:23 +0000
Subject: Bug #64543 [Opn->Nab]: Incorrect result of round
References: 1  Groups: php.bugs 
Request: Send a blank email to php-bugs+get-178170@lists.php.net to get a copy of this message 
Edit report at https://bugs.php.net/bug.php?id=64543&edit=1

 ID:                 64543
 Updated by:         nikic@php.net
 Reported by:        dev at medifirst dot fr
 Summary:            Incorrect result of round
-Status:             Open
+Status:             Not a bug
 Type:               Bug
 Package:            Math related
 Operating System:   Linux or Windows
 PHP Version:        5.4.13
 Block user comment: N
 Private report:     N

 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://www.floating-point-gui.de/

Thank you for your interest in PHP.

"precision" is the display precision. If you increase it you start seeing the rounding
errors inherent to the floating point type.


Previous Comments:
------------------------------------------------------------------------
[2013-03-28 16:28:55] dev at medifirst dot fr

Description:
------------
The "round" function returns a bad value if "precision" > 17.


Test script:
---------------
php.ini
precision = 20



php -r "echo round(5.554, 2)"



Expected result:
----------------
5.55 is the expected value

Actual result:
--------------
5.5499999999999998224 is the incorrect result


------------------------------------------------------------------------



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Edit this bug report at https://bugs.php.net/bug.php?id=64543&edit=1

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