[issue12211] Better document math.copysign behavior.

Mark Dickinson added the comment: Thanks! (And apologies for the nitpicking.) -- ___ Python tracker ___ ___ Python-bugs-list mailing

[issue12211] Better document math.copysign behavior.

Roundup Robot added the comment: New changeset b01f4ed077fa by Andrew Kuchling in branch '3.3': #12211: remove paragraph about NaNs http://hg.python.org/cpython/rev/b01f4ed077fa -- ___ Python tracker __

[issue12211] Better document math.copysign behavior.

Mark Dickinson added the comment: > It seems to just copy the sign bit no matter what x and y are. Yep, that's exactly what happens. The sign bit from y just gets blindly transferred to x, with no regard to any meaning of x or y. So it works exactly the same way for zeros, NaNs, infinities,

[issue12211] Better document math.copysign behavior.

A.M. Kuchling added the comment: Actually ISTM the 'if x is NaN' sentence can also go; it seems to just copy the sign bit no matter what x and y are. >>> from math import * >>> nan = float('nan') >>> neg = -nan >>> copysign(+1, copysign(nan, neg)) -1.0 -- _

[issue12211] Better document math.copysign behavior.

Mark Dickinson added the comment: More examples, showing that `y` is not ignored when `x` is a NaN. >>> result1 = copysign(float('nan'), 1.0) >>> result2 = copysign(float('nan'), -1.0) >>> copysign(1.0, result1) # result1 is a NaN whose sign bit is cleared. 1.0 >>> copysign(1.0, result2) # res

[issue12211] Better document math.copysign behavior.

A.M. Kuchling added the comment: OK; I'll just drop the 'If y is NaN' sentence. -- ___ Python tracker ___ ___ Python-bugs-list mailing

[issue12211] Better document math.copysign behavior.

Mark Dickinson added the comment: The paragraph about NaNs isn't correct. For example: >>> from math import copysign >>> copysign(1.0, float('nan')) 1.0 >>> copysign(1.0, -float('nan')) -1.0 Though it doesn't really make sense to talk about 'positive' or 'negative' NaNs, a NaN still has a sig

[issue12211] Better document math.copysign behavior.

A.M. Kuchling added the comment: Applied. I added two sentences describing the NaN behaviour. -- nosy: +akuchling resolution: -> fixed stage: patch review -> committed/rejected status: open -> closed ___ Python tracker

[issue12211] Better document math.copysign behavior.

Roundup Robot added the comment: New changeset 3ad7725b5013 by Andrew Kuchling in branch '3.3': #12211: clarify math.copysign() documentation and docstring http://hg.python.org/cpython/rev/3ad7725b5013 -- nosy: +python-dev ___ Python tracker

[issue12211] Better document math.copysign behavior.

Changes by Terry J. Reedy : -- versions: +Python 3.4 -Python 3.2 ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe:

[issue12211] Better document math.copysign behavior.

Terry J. Reedy added the comment: I agree with adding '(absolute value)'. I think the following covers the NaN behavior. "NaN acts as a positive value that cannot be negated." This should be added to both doc and docstring. I do not think we generally specify the nan behavior for each functio

[issue12211] Better document math.copysign behavior.

Sandro Tosi added the comment: well, what I actually meant is to describe the behavior in case one (or both) of the arguments is NaN (so not cut&pasting the code), while the example was just provided as a quick reference. -- ___ Python tracker

[issue12211] Better document math.copysign behavior.

umedoblock added the comment: sandro: OK, I attached the new patch. -- Added file: http://bugs.python.org/file22480/issue_12211_2.patch ___ Python tracker ___ __

[issue12211] Better document math.copysign behavior.

Sandro Tosi added the comment: Taken from http://www.slac.stanford.edu/comp/unix/package/rtems/doc/html/libm/libm.info.copysign.html i'd suggest to extend Return a float with the magnitude of x to Return a float with the magnitude (absolute value) of x It could probably help people les

[issue12211] Better document math.copysign behavior.

umedoblock added the comment: I'm late, sorry. I attached the patch for math.rst and mathmodule.c. -- Added file: http://bugs.python.org/file22278/issue_12211.patch ___ Python tracker

[issue12211] Better document math.copysign behavior.

Mark Dickinson added the comment: > I think we should include the "On a platform ..." Sure, sounds good. One of the main things that makes copysign useful is that it distinguishes between -0.0 and 0.0. -- ___ Python tracker

[issue12211] Better document math.copysign behavior.

Terry J. Reedy added the comment: Third party refers to things other than Pythonx.y code For instance, distutils2/distribute was for some years developed separately from the main codebase and was recently merged into the 3.3 repository. While separate, its issues were '3rd party'. That has no