[Numpy-discussion] ANN: NumPy 1.2.0

Matthieu Brucher matthieu.brucher@gmail....
Mon Sep 29 05:33:32 CDT 2008


2008/9/29 Pauli Virtanen <pav@iki.fi>:
> Mon, 29 Sep 2008 12:07:53 +0200, Matthieu Brucher wrote:
>
>>>>>> np.log(-1 + 0j)
>>> 3.1415926535897931j
>>>>>> np.log(-1 - 1e-99j)
>>> -3.1415926535897931j
>>>>>> np.log(-1 + 1e-99j)
>>> 3.1415926535897931j
>>>
>>> I'd guess this is typically harmless, but may lead to problems if your
>>> code relies on the choice of branch at the branch cut.
>>>
>>> Could you check if this is really the case? If log seems to work OK,
>>> then it's a problem with the test and not the functions.
>>
>> The result is what you expected.
>
> Do you mean that the problem is with the test, or with the branch cut of
> log?

I don't know, but the results are :

>>> np.log(-1 + 0j)
3.1415926535897931j
>>> np.log(-1 - 1e-99j)
-3.1415926535897931j
>>> np.log(-1 + 1e-99j)
3.1415926535897931j

Matthieu
-- 
French PhD student
Information System Engineer
Website: http://matthieu-brucher.developpez.com/
Blogs: http://matt.eifelle.com and http://blog.developpez.com/?blog=92
LinkedIn: http://www.linkedin.com/in/matthieubrucher


More information about the Numpy-discussion mailing list