Add expit function

[OmarManzoor]

CC: @lucascolley

I started with adding this simple function although I am not sure whether we need to add it at all. However does the format look fine. I think we might need more tests that test for dtypes and devices.

Also I am not sure how do I set this up locally to run tests. Do I need to install it? I was simply trying to configure the tests in Visual Studio code on a windows machine but it gives the following error:

from array_api_extra._lib import Backend
E   ModuleNotFoundError: No module named 'array_api_extra'

[lucascolley]

Also I am not sure how do I set this up locally to run tests. Do I need to install it?

thanks @OmarManzoor, have you read http://data-apis.org/array-api-extra/contributing.html ? That details the recommended development workflow.

If you don't want to use Pixi, then you could probably fix the error you are seeing with pip install -e ..

I am not sure whether we need to add it at all

I think we could. But I think I would actually prefer that this was first implemented as a "generic_implementation" in https://github.com/scipy/scipy/blob/main/scipy/special/_support_alternative_backends.py. After that point, we could consider making it available via xpx for older SciPy versions. Would you be willing to open a PR at SciPy for that?

[OmarManzoor]

@lucascolley Thank you for your reply. Currently I think it might be a bit difficult for me to also setup and contribute on scipy.

Also thanks for sharing the contributing guide. I missed reading that.

In any case I think let's close this PR for now. What do you think?

[lucascolley]

Sure, we can close this. Would you like to try another function? Maybe isin?