[Numpy-discussion] abs for max negative integers - desired behavior?
"V. Armando Solé"
Wed Oct 12 03:18:19 CDT 2011
From a pure user perspective, I would not expect the abs function to
return a negative number. Returning +127 plus a warning the first time
that happens seems to me a good compromise.
On 12/10/2011 09:46, David Cournapeau wrote:
> On Tue, Oct 11, 2011 at 8:16 PM, Charles R Harris
> <firstname.lastname@example.org> wrote:
>> On Tue, Oct 11, 2011 at 12:23 PM, Matthew Brett<email@example.com>
>>> I recently ran into this:
>>> In : arr = np.array(-128, np.int8)
>>> In : arr
>>> Out: array(-128, dtype=int8)
>>> In : np.abs(arr)
>>> Out: -128
>> This has come up for discussion before, but no consensus was ever reached.
>> One solution is for abs to return an unsigned type, but then combining that
>> with signed type of the same number of bits will cause both to be cast to
>> higher precision. IIRC, matlab was said to return +127 as abs(-128), which,
>> if true, is quite curious.
> In C, abs(INT_MIN) is undefined, so both 127 and -128 work :)
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