[Numpy-discussion] Sign of NaN

[Stephan Hoyer]

On Tue, Sep 29, 2015 at 8:13 AM, Charles R Harris <charlesr.harris at gmail.com
> wrote:

> Due to a recent commit, Numpy master now raises an error when applying the
> sign function to an object array containing NaN. Other options may be
> preferable, returning NaN for instance, so I would like to open the topic
> for discussion on the list.
>

We discussed this last month on the list and on GitHub:
https://mail.scipy.org/pipermail/numpy-discussion/2015-August/073503.html
https://github.com/numpy/numpy/issues/6265
https://github.com/numpy/numpy/pull/6269/files

The discussion was focused on what to do in the generic fallback case. Now
that I think about this more, I think it makes sense to explicitly check
for NaN in the unorderable case, and return NaN is the input is NaN. I
would not return NaN in general from unorderable objects, though -- in
general we should raise an error.

It sounds like Allan has already fixed this in his PR, but it also would
not be hard to add that logic to the existing code. Is this code in the
NumPy 1.10?

Stephan
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