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Doc Bug #66288 pow() gives unexpected results if exponent is negative
Submitted: 2013-12-13 16:11 UTC Modified: 2013-12-14 00:20 UTC
From: mattT1227 at gmail dot com Assigned:
Status: Not a bug Package: *General Issues
PHP Version: 5.5.7 OS:
Private report: No CVE-ID: None
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 [2013-12-13 16:11 UTC] mattT1227 at gmail dot com 
Description:
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From manual page: http://www.php.net/function.pow
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At least show example that negative exponents are not correctly implemented by pow.

Note, reporting system shows this problem has been suspended. It is still a problem. 

Test script:
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echo pow(4, -2); // should be same as square root of 4

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 [2013-12-13 18:24 UTC] aharvey@php.net
-Status: Open +Status: Not a bug
 [2013-12-13 18:24 UTC] aharvey@php.net 
pow() handles negative exponents fine: pow(4, -2) is 0.0625, which seems correct to me and also to Wolfram|Alpha: http://www.wolframalpha.com/input/?i=4^-2

Closing not a bug.
 [2013-12-13 22:15 UTC] rasmus@php.net 
By the way, where is the suspended bug on this? We should mark that as Not-a-bug as well. 4^-2 is the same as 1/(4^2) which is most definitely not the same as the square root of 4. Where in the world did you get that from?
 [2013-12-14 00:20 UTC] datibbaw@php.net 
The square root of 4 is calculated with a power of 1/2, i.e.

pow(4, 0.5) == float(2)
 
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