Opened 4 years ago
Closed 4 years ago
#22026 closed defect (fixed)
Doctests: Even reals are integers
Reported by: | pelegm | Owned by: | |
---|---|---|---|
Priority: | major | Milestone: | sage-8.0 |
Component: | symbolics | Keywords: | is_integer, assume |
Cc: | Merged in: | ||
Authors: | Ralf Stephan | Reviewers: | Travis Scrimshaw |
Report Upstream: | N/A | Work issues: | |
Branch: | 81e3fba (Commits, GitHub, GitLab) | Commit: | 81e3fbabc4d05832f20d04ff216e112e607aa1d1 |
Dependencies: | #22219 | Stopgaps: |
Description (last modified by )
Check this:
sage: assume(x, 'even') sage: assume(x, 'real') sage: simplify((-1)**x) 1 sage: x.is_integer() False
At least for real numbers (or even for complex numbers), an even number should be assumed to be an integer.
This is how it works in SymPy:
In [2]: x = Symbol('x', even=True) In [3]: x.is_integer Out[3]: True
Was supposed to be fixed in pynac-0.7.4. This will also work and should be doctested here:
sage: sage: assume(x, 'even') ....: sage: assume(x, 'real') ....: sage: (-1)^x 1 sage: (-gamma(pi))^x gamma(pi)^x
Change History (11)
comment:1 Changed 4 years ago by
comment:2 Changed 4 years ago by
Yes, Maxima knows. The inference logic however is in Pynac.
comment:3 Changed 4 years ago by
- Report Upstream changed from N/A to Reported upstream. Developers acknowledge bug.
This is now https://github.com/pynac/pynac/issues/225
comment:4 Changed 4 years ago by
- Dependencies set to pynac-0.7.4
comment:5 Changed 4 years ago by
- Description modified (diff)
- Report Upstream changed from Reported upstream. Developers acknowledge bug. to Fixed upstream, but not in a stable release.
comment:7 Changed 4 years ago by
- Summary changed from Even reals are integers to Doctests: Even reals are integers
Issue is fixed. Only doctests needed.
comment:8 Changed 4 years ago by
- Branch set to u/rws/doctests__even_reals_are_integers
comment:9 Changed 4 years ago by
- Commit set to 81e3fbabc4d05832f20d04ff216e112e607aa1d1
- Dependencies changed from pynac-0.7.4 to #22219
- Milestone changed from sage-7.5 to sage-8.0
- Report Upstream changed from Fixed upstream, but not in a stable release. to N/A
- Status changed from new to needs_review
New commits:
81e3fba | 22026: Doctest: Even reals are integer
|
comment:10 Changed 4 years ago by
- Reviewers set to Travis Scrimshaw
- Status changed from needs_review to positive_review
LGTM.
comment:11 Changed 4 years ago by
- Branch changed from u/rws/doctests__even_reals_are_integers to 81e3fbabc4d05832f20d04ff216e112e607aa1d1
- Resolution set to fixed
- Status changed from positive_review to closed
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I wasn't sure if I should report this as a defect or as an enhancement.
I'll add that if one tries
an error is raised:
so "someone" knows
x
is an integer...