[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

Changes by Donald Stufft : -- pull_requests: +889 ___ Python tracker ___ ___

[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

Changes by Larry Hastings : -- pull_requests: +620 ___ Python tracker ___ ___

[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

Mark Dickinson added the comment: I'm a bit puzzled about where the commit 4ddd89780fdb823f427c743ea7326a3c958a2f4b came from, but as far as I can tell the changes to 2.7, 3.5, 3.6 and master are all okay. All fixed. Thanks for the report! -- resolution: -> fixed stage: patch review

[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

Mark Dickinson added the comment: New changeset d9b3cdd137239a5913de2252c3ce269e35ac63d2 by GitHub in branch '3.6': bpo-29602: fix signed zero handling in complex constructor. (#203) (#206) https://github.com/python/cpython/commit/d9b3cdd137239a5913de2252c3ce269e35ac63d2 --

[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

Mark Dickinson added the comment: New changeset 0936a00fe035e3e52c30bcbc59668dc0f519ced6 by GitHub in branch '3.5': bpo-29602: fix signed zero handling in complex constructor. (#203) (#205) https://github.com/python/cpython/commit/0936a00fe035e3e52c30bcbc59668dc0f519ced6 --

[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

Mark Dickinson added the comment: New changeset c0b336e0ada74b1242b9ef10c19eb87b0a21d106 by GitHub in branch '2.7': bpo-29602: fix signed zero handling in complex constructor (#204) https://github.com/python/cpython/commit/c0b336e0ada74b1242b9ef10c19eb87b0a21d106 --

[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

Changes by Mark Dickinson : -- pull_requests: +175 ___ Python tracker ___ ___

[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

Changes by Mark Dickinson : -- pull_requests: +174 ___ Python tracker ___ ___

[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

Changes by Serhiy Storchaka : -- pull_requests: -171 ___ Python tracker ___ ___

[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

Changes by Mark Dickinson : -- pull_requests: +173 ___ Python tracker ___ ___

[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

Mark Dickinson added the comment: New changeset 4ddd89780fdb823f427c743ea7326a3c958a2f4b by Mark Dickinson in branch 'bpo-29549-backport': bpo-29602: fix signed zero handling in complex constructor https://github.com/python/cpython/commit/4ddd89780fdb823f427c743ea7326a3c958a2f4b --

[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

Changes by Serhiy Storchaka : -- pull_requests: +171 ___ Python tracker ___ ___

[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

Mark Dickinson added the comment: New changeset 112ec38c15b388fe025ccb85369a584d218b1160 by GitHub in branch 'master': bpo-29602: fix signed zero handling in complex constructor. (#203) https://github.com/python/cpython/commit/112ec38c15b388fe025ccb85369a584d218b1160 --

[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

Mark Dickinson added the comment: Created https://github.com/python/cpython/pull/203, but I feel bad for having my name on the commits. :-( -- ___ Python tracker

[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

Changes by Mark Dickinson : -- pull_requests: +169 ___ Python tracker ___ ___

[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

Serhiy Storchaka added the comment: I pushed changes to my fork but when try to create a pull request it contains unrelated changes. Seems I do something wrong. -- ___ Python tracker

[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

Mark Dickinson added the comment: complex-constructor-from-complex2.patch looks good to me. What happens now? I presume we can no longer push to hg.python.org? So one of us needs to make a PR on GitHub and another review it? -- ___ Python tracker

[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

Changes by Serhiy Storchaka : Added file: http://bugs.python.org/file46654/complex-constructor-from-complex2.patch ___ Python tracker

[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

Armin Rigo added the comment: 4 lines before the new "ci.real = cr.imag;", we have "cr.imag = 0.0; /* Shut up compiler warning */". The comment is now wrong: we really need to set cr.imag to 0.0. -- ___ Python tracker

[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

Serhiy Storchaka added the comment: Proposed patch fixes constructing complex from complex. But in future versions perhaps it is worth to disallow passing complex argument to two-arguments complex constructor. -- keywords: +patch stage: needs patch -> patch review Added file:

[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

Mark Dickinson added the comment: Armin, Victor: please open other issues for these discussions; they're unrelated to the bug reported here. Also, see #27363, #17336, #22548, #25839. -- ___ Python tracker

[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

STINNER Victor added the comment: IMHO it would be less surprising if repr(complex) would return 'complex(..., ...)': it would be possible to copy/paste and get the result value. I was bitten multiple time by the zero sign with complex numbers... -- nosy: +haypo

[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

Armin Rigo added the comment: Maybe I should be more explicit: what seems strange to me is that some complex numbers have a repr that, when entered in the source, produces a different result. For example, if you want the result ``(-0-0j)`` you have to enter something different. However, I

[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

Mark Dickinson added the comment: > It's unclear if the signs of the two potential zeroes in a complex number > have a meaning Yes, very much so. The signs are important in determining which side of a branch cut to use in the various cmath functions. --

[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

Mark Dickinson added the comment: Armin: that's a separate issue, and is expected behaviour. >>> -(0j) # this is -(0+0j) (-0-0j) Yes: 0j is complex(0.0, 0.0); negating negates both the real and imaginary parts. >>> (-0-0j) # but this equals to the difference between 0 and 0+0j 0j

[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

Armin Rigo added the comment: CPython 2.7 and 3.5 have issues with the sign of zeroes even without any custom class: >>> -(0j) # this is -(0+0j) (-0-0j) >>> (-0-0j) # but this equals to the difference between 0 and 0+0j 0j >>> (-0.0-0j) # this is the difference between -0.0 and

[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

Changes by Serhiy Storchaka : -- nosy: +serhiy.storchaka ___ Python tracker ___

[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

Mark Dickinson added the comment: Looking at the source, there's also an issue with complex subclasses here: >>> class C(complex): ... pass ... >>> complex(C(-0j)) (-0+0j) >>> complex(-0j) (-0-0j) -- ___ Python tracker

[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

Changes by Mark Dickinson : -- assignee: -> mark.dickinson ___ Python tracker ___ ___

[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

Mark Dickinson added the comment: Confirmed on my machine. The effect of the source is to do `complex(complex(x), 0.0)` in this case, which isn't correct. -- components: +Interpreter Core stage: -> needs patch versions: +Python 3.5, Python 3.7 ___

[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

Changes by Xiang Zhang : -- nosy: +mark.dickinson ___ Python tracker ___ ___

[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

Changes by Steven D'Aprano : -- nosy: +steven.daprano ___ Python tracker ___ ___

[issue29602] complex() on object with __complex__ function loses sign of zero imaginary part

New submission from Tom Krauss: Consider the following simple class that provides a "__complex__" method. class C(object): def __init__(self, x): self.x = x def __complex__(self): return self.x x=C(-0j) PYTHON 2.7.13 >>> x.x -0j >>> complex(x) 0j PYTHON 3.6 >>> x.x (-0-0j) >>>