add logsubexp(x,y)

[cossio]

This is useful in some contexts. Other libraries have this, for example, https://www.tensorflow.org/probability/api_docs/python/tfp/math/log_sub_exp

If this gets merged please tag a release (I bumped the version here).

[cossio]

Merge?

[nalimilan]

I have the feeling we discussed similar xlogx issues recently but I can't find where...

[nalimilan]

Thanks!

[cossio]

@nalimilan Thank you for taking a look!
Nothing left to merge? Also please tag a release with this.

[nalimilan]

After considering this again, I found out that x log x has no limit in 0 for complex numbers. So the docstring isn't correct for them. How about just mentioning that we return zero for zero (for both xlogx and xlogy, like Numpy does? We could still mention that it's consistent with the limit for reals. See also the previous discussion we had about this (I just found it again!): #87 (comment)

[cossio]

Good point @nalimilan. Done.

[cossio]

Please tag a release with this. Thanks!