On Thu, Aug 04, 2016 at 09:46:05PM +0200, Victor Stinner wrote:
A suggest to start to write a short PEP as the math.is_close() PEP since there are subtle issues like NaN (float but also Decimal!) and combinations of numerical types (int, float, complex, Decimal, Fraction, numpy scalars like float16, ...).
Maybe a PEP is not needed, I didn't read carefully the thread to check if there is a consensus or not.
No consensus.
I dislike the idea of modifying min() and max() to add special cases for float NaN and decimal NaN.
min() and max() currently return NANs when given a NAN and number, but I don't know if that is deliberate or accidental. The IEEE-754 standard says that min(x, NAN) and max(x, NAN) should return x. https://en.wikipedia.org/wiki/IEEE_754_revision#min_and_max
Which type do you expect for fmax(int, int)? Should it be int or float?
int.
Should fmax(Decimal, float) raise an error, return a float or return a Decimal?
Comparisons between float and Decimal no longer raise: py> Decimal(1) < 1.0 False so I would expect that fmax would return the larger of the two. If the larger is a float, it should return a float. If the larger is a Decimal, it should return a Decimal. If the two values are equal, it's okay to pick an arbitrary one. -- Steve