[Numpy-discussion] Bug in logaddexp2.reduce

Ryan May rmay31@gmail....
Wed Mar 31 20:35:51 CDT 2010


On Wed, Mar 31, 2010 at 5:37 PM, Warren Weckesser
<warren.weckesser@enthought.com> wrote:
> T J wrote:
>> On Wed, Mar 31, 2010 at 1:21 PM, Charles R Harris
>> <charlesr.harris@gmail.com> wrote:
>>
>>> Looks like roundoff error.
>>>
>>>
>>
>> So this is "expected" behavior?
>>
>> In [1]: np.logaddexp2(-1.5849625007211563, -53.584962500721154)
>> Out[1]: -1.5849625007211561
>>
>> In [2]: np.logaddexp2(-0.5849625007211563, -53.584962500721154)
>> Out[2]: nan
>>
>
> Is any able to reproduce this?  I don't get 'nan' in either 1.4.0 or
> 2.0.0.dev8313 (32 bit Mac OSX).  In an earlier email T J reported using
> 1.5.0.dev8106.

No luck here on Gentoo Linux:

Python 2.6.4 (r264:75706, Mar 11 2010, 09:29:48)
[GCC 4.3.4] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import numpy as np
>>> np.logaddexp2(-0.5849625007211563, -53.584962500721154)
-0.58496250072115619
>>> np.logaddexp2(-1.5849625007211563, -53.584962500721154)
-1.5849625007211561
>>> np.version.version
'2.0.0.dev8313'

Ryan

-- 
Ryan May
Graduate Research Assistant
School of Meteorology
University of Oklahoma


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