Strange behaviour of Numeric.where

[Otto T Hyvarinen]

Perhaps there is a rational explanation to this:
"
Python 2.0 (#5, Feb 20 2001, 11:00:04)
[GCC 2.95.3 19991030 (prerelease)] on linux2
Type "copyright", "credits" or "license" for more information.
>>> import Numeric
>>> a=Numeric.array([1,2,0,4,1])
>>> Numeric.where(Numeric.equal(a,0),0,1/a)
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
ZeroDivisionError: divide by zero
>>> Numeric.where(Numeric.equal(a,0),0,1./a)
array([ 1.  ,  0.5 ,  0.  ,  0.25,  1.  ])
>>>  
"
The first version is a bit stupid, because it will only return ones and
zeros. But why it returns division by zero is beyond me.

I tried this on Python1.5.2 with Irix, and got the same results except that
with Irix I get:
"
>>> Numeric.where(Numeric.equal(a,42),0,1/a)
array([1, 0, 0, 0, 1])
"
and with Linux:
"
>>> Numeric.where(Numeric.equal(a,42),0,1/a)
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
ZeroDivisionError: divide by zero    
"

Strange.


Otto Hyvärinen, otto.hyvarinen at fmi.fi