[Numpy-discussion] making the distinction between -0.0 and 0.0..
Christian Heimes
lists@cheimes...
Tue Sep 29 15:53:52 CDT 2009
Christopher Barker wrote:
> Hi folks,
>
> This isn't really a numpy question, and I'm doing this with regular old
> python, but I figure you are the folks that would know this:
>
> How do I get python to make a distinction between -0.0 and 0.0? IN this
> case, I'm starting with user input, so:
How about using atan2()? :)
>>> from math import atan2
>>> atan2(-0., -1.)
-3.1415926535897931
>>> atan2(0., -1.)
3.1415926535897931
from math import atan2
def sign(x):
if x > 0.:
return +1
if x < 0.:
return -1
# x == 0. or -0.
if atan2(x, -1.) > 0:
return +1
else:
return -1
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