#17984: fix Parent.__contains__
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Reporter: rws | Owner:
Type: | Status: needs_info
enhancement | Milestone: sage-6.6
Priority: major | Resolution:
Component: basic | Merged in:
arithmetic | Reviewers:
Keywords: | Work issues:
Authors: Ralf | Commit:
Stephan | 544450ea18ed2778953141bab8feced61237556e
Report Upstream: N/A | Stopgaps:
Branch: |
u/rws/17984 |
Dependencies: |
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Changes (by rws):
* status: needs_review => needs_info
Old description:
> In the catch-all `structure/parent.pyx:Parent.__contains__` we depend on
> the construction `bool(item==self(item))` to get the right result for,
> e.g. `sqrt(3) in RR/CC` but `bool(RR/CC(sqrt(3))==sqrt(3))` being
> `False`. In order to make it more reliable dedicated `__contains__`
> methods for both rings are needed.
>
> Moreover, until now Maxima is used for this which is slow and completely
> unnecessary.
New description:
In the catch-all `structure/parent.pyx:Parent.__contains__` we depend on
the construction `bool(item==self(item))` to get the right result for,
e.g. `sqrt(3) in RR/CC` but `bool(RR/CC(sqrt(3))==sqrt(3))` being `False`.
In order to make it more reliable the way we treat inclusion in inexact
rings needs to be reconsidered.
Previously this ticket proposed that:
...dedicated `__contains__` methods for both rings are needed.
Moreover, until now Maxima is used for this which is slow and completely
unnecessary.
--
Comment:
Replying to [comment:29 vdelecroix]:
> I do not like the fact that we treat `RR` as a subset of the real
numbers and at the same time a field
What would be consequences of removing it from the set (apart from
documentation issues)?
--
Ticket URL: <http://trac.sagemath.org/ticket/17984#comment:30>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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