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Bug #54224 Sum comutative operation fails with minus on front
Submitted: 2011-03-11 12:31 UTC Modified: 2011-03-11 19:21 UTC
Votes:1
Avg. Score:5.0 ± 0.0
Reproduced:0 of 0 (0.0%)
From: philip dot almeida at freedomson dot com Assigned:
Status: Not a bug Package: Math related
PHP Version: Irrelevant OS: Linux
Private report: No CVE-ID: None
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From: philip dot almeida at freedomson dot com
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 [2011-03-11 12:31 UTC] philip dot almeida at freedomson dot com 
Description:
------------
Making a comutative sum operation the result does not return the expected value.

Test script:
---------------
echo -6.3536+5+1.3536;
= -2.22044604925E-16

echo -6.3537+5+1.3537
= 0

Expected result:
----------------
Always 0

Actual result:
--------------
-2.22044604925E-16

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 [2011-03-11 19:21 UTC] scottmac@php.net
-Status: Open +Status: Bogus
 [2011-03-11 19:21 UTC] scottmac@php.net 
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.
 
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