[Numpy-discussion] 0/0 is 0 or nan?

Robert Kern robert.kern@gmail....
Fri Mar 9 12:03:33 CST 2007

Christopher Barker wrote:
> Robert Kern wrote:
>> However, I believe that divide() on two Python ints goes through a different
>> path than for numpy arrays and numpy scalars. Rather, they are recognized as
>> objects that implement .__div__(), and that is called instead.
> Then wouldn't this be different:
>  >>> a = N.array(0, dtype=N.int)
>  >>> b = N.array(0, dtype=N.int)
>  >>> N.divide(a,b)
> 0

What version of numpy are you using?

In [13]: from numpy import *

In [14]: a = array(0, dtype=int)

In [15]: b = array(0, dtype=int)

In [16]: divide(a, b)
Warning: divide by zero encountered in divide
Out[16]: 0

In [17]: geterr()
Out[17]: {'divide': 'print', 'invalid': 'print', 'over': 'print', 'under': 'ignore'}

In [18]: import numpy

In [19]: numpy.__version__
Out[19]: '1.0.2.dev3569'

Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
 that is made terrible by our own mad attempt to interpret it as though it had
 an underlying truth."
  -- Umberto Eco

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