Bug #66132 [Opn->Nab]: X*5/X where X is floating point number is greater than 5

Edit report at https://bugs.php.net/bug.php?id=66132&edit=1

 ID:                 66132
 Updated by:         [email protected]
 Reported by:        utilmind at gmail dot com
 Summary:            X*5/X where X is floating point number is greater
                     than 5
-Status:             Open
+Status:             Not a bug
 Type:               Bug
 Package:            PHP-GTK related
 Operating System:   Any, tested in Win32 and CentOS
 PHP Version:        5.4.22
 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.

php > ini_set("precision", 17);
php > $n = (3.89880952381*5/3.89880952381); // result will be a very bit greater than 5
php > var_dump($n);
float(5.0000000000000009)


Previous Comments:
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[2013-11-21 00:19:36] [email protected]

This is an PHP main package bug

Confirmed

Version: PHP 5.5.1-2 (built: Aug  5 2013 14:10:28)
OS: Linux version 3.10-2-amd64 #1 SMP Debian 3.10.5-1 (2013-08-07)

------------------------------------------------------------------------
[2013-11-20 23:53:46] utilmind at gmail dot com

Description:
------------
It's probably bug with conversion from floating point number, or bug with comparision between types. We know that X*5/5 is 5. Even PHP returns 5, however, sometimes, returned value appears to be greater than 5.

Test script:
---------------
$n = (3.89880952381*5/3.89880952381); // result will be exactly 5
print $n.'!=5 ? '.($n>5); // here it appears that 5 is greater than 5



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Edit this bug report at https://bugs.php.net/bug.php?id=66132&edit=1