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Doc Bug #52748 bcpow() - scale parameter doesn't influensce the result string
Submitted: 2010-08-30 22:52 UTC Modified: 2010-09-09 07:45 UTC
From: k.schroeder@php.net Assigned: aharvey (profile)
Status: Closed Package: Documentation problem
PHP Version: trunk-SVN-2010-08-30 (SVN) OS: Windows XP
Private report: No CVE-ID: None
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 [2010-08-30 22:52 UTC] k.schroeder@php.net 
Description:
------------
Executing bcpow('-2', '5') and bcpow('-2', '5', 2) results in same string ("-32").

Test script:
---------------
--TEST--
bcpow() - scale parameter doesn't influensce the result string
--SKIPIF--
<?php if(! extension_loaded('bcmath')) print 'extension bcmath not loaded'; ?>
--INI--
bcmath.scale=0
--FILE--
<?php
var_dump(bcpow('-2', '5'));
var_dump(bcpow('-2', '5', 2));
?>
--EXPECT--
string(3) "-32"
string(5) "-32.00"

Expected result:
----------------
string(3) "-32"
string(5) "-32.00"

Actual result:
--------------
string(3) "-32"
string(3) "-32"

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 [2010-09-09 07:37 UTC] aharvey@php.net
-Status: Open +Status: Assigned -Type: Bug +Type: Documentation Problem -Package: BC math related +Package: Documentation problem -Assigned To: +Assigned To: aharvey
 [2010-09-09 07:37 UTC] aharvey@php.net 
It actually does influence the result, but libbcmath's bc_raise() function manipulates the scale internally for its own purposes, so you may end up with a result of lesser scale than the scale parameter would indicate. (It appears that you'll never end up with a result of greater scale, though.)

Morphing into a doc bug, since libbcmath itself appears to behave logically; I'll add a note to the bcpow() manual page that the result scale may not be quite what you expect.
 [2010-09-09 07:45 UTC] aharvey@php.net 
Automatic comment from SVN on behalf of aharvey
Revision: http://svn.php.net/viewvc/?view=revision&amp;revision=303202
Log: Fix (doc) bug #52748 (bcpow() - scale parameter doesn't influensce the result
string) by adding a clarifying note about bcpow's exact behaviour when dealing
with scale.
 [2010-09-09 07:45 UTC] aharvey@php.net
-Status: Assigned +Status: Closed
 [2010-09-09 07:45 UTC] aharvey@php.net 
This bug has been fixed in the documentation's XML sources. Since the
online and downloadable versions of the documentation need some time
to get updated, we would like to ask you to be a bit patient.

Thank you for the report, and for helping us make our documentation better.
 
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