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Request #76578 ** operator and negative base
Submitted: 2018-07-04 12:13 UTC Modified: 2018-07-04 18:49 UTC
From: amenshchikov at gmail dot com Assigned:
Status: Wont fix Package: *General Issues
PHP Version: 7.2.7 OS: Debian 9
Private report: No CVE-ID: None
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 [2018-07-04 12:13 UTC] amenshchikov at gmail dot com 
Description:
------------
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From manual page: http://www.php.net/language.operators.arithmetic
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When I try to raise number -9 to the power of 0.5 (take a root of even degree), I have -3 as result. But I think that NaN should be a more correct in this case.

Test script:
---------------
echo -9**0.5;

Expected result:
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NAN

Actual result:
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-3

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 [2018-07-04 12:17 UTC] requinix@php.net
-Status: Open +Status: Wont fix -Package: PHP Language Specification +Package: *General Issues
 [2018-07-04 12:17 UTC] requinix@php.net 
** having higher precedence than - was specifically discussed when the operator was being added.
http://php.net/manual/en/language.operators.precedence.php
https://wiki.php.net/rfc/pow-operator
 [2018-07-04 18:49 UTC] rasmus@php.net 
Or in other words, what you are doing is -(9 ** 0.5) which is indeed -3.
If you really mean to raise -9 to 0.5, do (-9)**0.5 and you will see you get NAN
 
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