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Bug #43746 unexpected result in round()
Submitted: 2008-01-04 05:46 UTC Modified: 2008-01-25 20:08 UTC
From: phil at phymoky dot com Assigned:
Status: Not a bug Package: Math related
PHP Version: 5.2.5 OS: Windows 2000
Private report: No CVE-ID: None
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From: phil at phymoky dot com
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 [2008-01-04 05:46 UTC] phil at phymoky dot com 
Description:
------------
unexpected result in round()

Reproduce code:
---------------
<?php
echo round(1234567, -5); // is 1.2E+6
echo round(1334567, -5); // is 1300000
echo round(1134567, -5); // is 1100000
?>

Expected result:
----------------
1200000
1300000
1100000

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 [2008-01-25 20:08 UTC] tony2001@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
 
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