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

Christopher Barker Chris.Barker@noaa....
Fri Mar 9 11:13:49 CST 2007


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

or to really make sure we're not using Python integers:

 >>> a = N.array(0, dtype=N.int16)
 >>> b = N.array(0, dtype=N.int16)
 >>> N.divide(a,b)
0

for completeness:
 >>> a = N.array(0, dtype=N.float)
 >>> b = N.array(0, dtype=N.float)
 >>> N.divide(a,b)
Warning: invalid value encountered in divide
nan

-Chris



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