#17984: Dedicated RR.__contains__() and CC.__contains__()
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Reporter: rws | Owner:
Type: | Status: needs_review
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 vdelecroix):
* cc: tmonteil (added)
Comment:
Replying to [comment:28 rws]:
> Replying to [comment:26 rws]:
> > So, pragmatically, every inexact ring needs a method
`is_exactly_representable(item)` in order to determine usefully if
`bool(item == RR(item))`.
> Ah okay, `RIF(1/5).is_exact` is implemented so we need the same method
elsewhere.
This method makes sense in `RIF` but not in `RR`: a number is exact in
`RIF` if the associated interval is a singleton. This is very different
from the proposition of having a method
`RR.is_exactly_representable(...)`.
I do not like the fact that we treat `RR` as a subset of the real numbers
and at the same time a field
{{{
sage: RR.is_field()
True
sage: RR in Fields()
True
}}}
Vincent
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Ticket URL: <http://trac.sagemath.org/ticket/17984#comment:29>
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