[Numpy-tickets] [NumPy] #301: power with negative argument returns 0

NumPy numpy-tickets at scipy.net
Sat Sep 30 17:18:36 CDT 2006


#301: power with negative argument returns 0
------------------------+---------------------------------------------------
 Reporter:  stefan      |       Owner:  somebody   
     Type:  defect      |      Status:  new        
 Priority:  normal      |   Milestone:  1.0 Release
Component:  numpy.core  |     Version:             
 Severity:  normal      |    Keywords:             
------------------------+---------------------------------------------------
 The power function returns an (incorrect) value for negative powers of
 integers:

 {{{
 In [1]: N.power(3,-2)
 Out[1]: 0
 }}}

 Unlike integer division, which is well defined, I am not sure what the
 behaviour of power should be. Tim Hochberg's comment on the topic can be
 seen on the mailing list thread at

 http://thread.gmane.org/gmane.comp.python.numeric.general/8418/focus=8418

 In short, it offers the possibility of making numpy.power behave like
 Python's math.pow, which always returns floats, whereas x**y will be
 equivalent to the Python ** integer behaviour.

-- 
Ticket URL: <http://projects.scipy.org/scipy/numpy/ticket/301>
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