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Bug #49112 Problem with float numbers - only in one case
Submitted: 2009-07-30 16:56 UTC Modified: 2009-07-30 17:12 UTC
From: marek at 3v dot ie Assigned:
Status: Not a bug Package: Math related
PHP Version: 5.2.10 OS: Fedora 9
Private report: No CVE-ID: None
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 [2009-07-30 16:56 UTC] marek at 3v dot ie
Description:
------------
When I try to substract specific float numbers I receive a wrong result


Reproduce code:
---------------
echo (35.19 - 31.69 - 3.50);
echo (36.19 - 31.69 - 2.50);

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

Actual result:
--------------
-3.5527136788005E-15

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 [2009-07-30 17:12 UTC] derick@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://docs.sun.com/source/806-3568/ncg_goldberg.html
 
Thank you for your interest in PHP.

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