[Numpy-discussion] abs for max negative integers - desired behavior?

Charles R Harris charlesr.harris at gmail.com
Tue Oct 11 15:16:39 EDT 2011


On Tue, Oct 11, 2011 at 12:23 PM, Matthew Brett <matthew.brett at gmail.com>wrote:

> Hi,
>
> I recently ran into this:
>
> In [68]: arr = np.array(-128, np.int8)
>
> In [69]: arr
> Out[69]: array(-128, dtype=int8)
>
> In [70]: np.abs(arr)
> Out[70]: -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.

<snip>

Chuck
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