[Numpy-discussion] Binary ufuncs: minimum

[Nathan Bell]

On Tue, May 27, 2008 at 5:39 PM, Christopher Barker
<Chris.Barker@noaa.gov> wrote:
>
> I'm not so sure. I know I wouldn't expect to get a different type back
> with a call to abs(). Do we really want to change that expectation just
> for the case of MIN_INT?
>
> While everyone is going to want an unsigned value when calling abs(),
> who knows if they might want to use negative numbers later? Like:
>
> x = abs(x)
> x *= -1
>
> Now what do we get/want?

IMO abs() returning non-negative numbers is a more fundamental
property.  In-place operations on integer arrays are somewhat
dangerous, and best left to more sophisticated users anyway.


Interestingly, MATLAB (v7.5.0) takes a different approach:

>> A = int8([ -128, 1])
A =
 -128    1
>> abs(A)
ans =
  127    1
>> -A
ans =
  127   -1


-- 
Nathan Bell wnbell@gmail.com
http://graphics.cs.uiuc.edu/~wnbell/