#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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Comment (by rws):
Replying to [comment:25 pbruin]:
> Elements of `RR` (except infinities and `NaN`) are certain fractions
whose numerator and denominator are bounded and whose denominator is a
power of 2. Hence 1/16 is representable in `RR`, but 1/3 is not.
So this would be similar (equal?) to what was recently said about `RIF` in
https://groups.google.com/d/topic/sage-devel/9MHkb4cUUHM/discussion
> Different people have different viewpoints about this, but above I was
thinking of elements of `RR` (again except infinities and `NaN`) as
exactly representing a certain subset of (mathematical) real numbers.
So, pragmatically, every inexact ring needs a method
`is_exactly_representable(item)` in order to determine usefully if
`bool(item == RR(item))`.
--
Ticket URL: <http://trac.sagemath.org/ticket/17984#comment:26>
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