php-documentation-list | 2003101

[PHP-DOC] #25751 [Opn->Ana]: pow() function return errors From: sniper <email protected>
Date: 10/03/03

 ID: 25751
 Updated by: sniper <email protected>
 Reported By: dbjm at comcast dot net
-Status: Open
+Status: Analyzed
-Bug Type: Math related
+Bug Type: Documentation problem
 Operating System: Windows 2000 & Linux 9
 PHP Version: 4.3.2
 New Comment:

There are some documentation problems:

1. pow() no longer shows any errors, even if parameters are invalid
2. pow(-1,1.1) produces complex number which PHP does not support.

For dbjm at comcast dot net:

Look manual for "is_finite()" function.

Previous Comments:
------------------------------------------------------------------------

[2003-10-03 18:12:12] dbjm at comcast dot net

Description:
------------
The pow() function returns incorrect numbers when using a negative
number base.

This is not a crisis to fix for me - I have worked around it.

Thanks for the great work on developing PHP.

Sincerely,

Dave

Reproduce code:
---------------
echo "pow(3.125, 3.125) = " . pow(3.125, 3.125). "<br>";
echo "pow(-3.125, 3.125) = " . pow(-3.125, 3.125). "<br>";
echo "pow(3.125, -3.125) = " . pow(3.125, -3.125). "<br>";
echo "pow(-3.125, -3.125) = " . pow(-3.125, -3.125). "<br>";

Expected result:
----------------
When the same calcualtion is made using Visual Basic the results are:

3.125 ^ 3.125 = 35.1889507775869
-3.125 ^ 3.125 = -35.1889507775869
3.125 ^ -3.125 = 2.84180112763389E-02
-3.125 ^ -3.125 = -2.84180112763389E-02

Actual result:
--------------
Windows 2000:
pow(3.125, 3.125) = 35.1889507776
pow(-3.125, 3.125) = -1.#IND
pow(3.125, -3.125) = 0.0284180112763
pow(-3.125, -3.125) = -1.#IND

Linux 9:
pow(3.125, 3.125) = 35.188950777587
pow(-3.125, 3.125) = NAN
pow(3.125, -3.125) = 0.028418011276339
pow(-3.125, -3.125) = NAN

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