On Thu, Aug 30, 2018 at 5:51 AM Nicolas Rolin <nicolas.rolin@tiime.fr> wrote:



Right, but we already have some special cases:

In [8]: Fraction(2, 3) ** Fraction(3, 1)
Out[8]: Fraction(8, 27)

Fraction.__pow__ already tries to return Fraction objects where possible.


I think the main point to see here is what the scope of a built-in function should be.
For a fraction module in the stdlib, I would expect that it handle "symbolically" any fraction multiplication or division of fractions, and integer power of fractions.
Those are simple and useful cases, that can arise a bit anywhere. Power of non-integer is a way more complex issue (notably because power of a non-integer is not a function), and returning the same output as float is at least an honest way of dealing with those cases.

But I'm only asking for fractional powers of -1, 0, and 1.  Is that really a complex issue?   

You are right that the fractional power of -1 and 1 has multiple values, but the fractional power of zero has a unique value.

I'm not really sure a stdlib should even try do deal with that. If I want to have a symbolic way of handling complex power of fractions, I should import a specific math library whose specific job is to get this right (the same way if you want to do matrix stuff you have to import numpy).

That's how I use the fractions package.  If you look at my example code, that seems like the kind of problem Fraction should make it easy to work with.  And yet, there was a wrinkle where I had to calculate Fraction(-1) ** Fraction(a, b).



--

Nicolas Rolin

--

---
You received this message because you are subscribed to a topic in the Google Groups "python-ideas" group.
To unsubscribe from this topic, visit https://groups.google.com/d/topic/python-ideas/aZIHpPhe0mw/unsubscribe.
To unsubscribe from this group and all its topics, send an email to python-ideas+unsubscribe@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.
_______________________________________________
Python-ideas mailing list
Python-ideas@python.org
https://mail.python.org/mailman/listinfo/python-ideas
Code of Conduct: http://python.org/psf/codeofconduct/

--

---
You received this message because you are subscribed to a topic in the Google Groups "python-ideas" group.
To unsubscribe from this topic, visit https://groups.google.com/d/topic/python-ideas/aZIHpPhe0mw/unsubscribe.
To unsubscribe from this group and all its topics, send an email to python-ideas+unsubscribe@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.