#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:20 pbruin]:
> I guess the first basic question is how to resolve the following
inconsistency:
> {{{
> sage: bool(RR(pi) == pi)
> True
> sage: bool(RR(sqrt(2)) == sqrt(2))
> False
> }}}
>...Hence I am tending towards the opinion that if `x` is some exact
element, then `bool(RR(x) == x)` should return `True` if and only if `x`
is exactly representable in `RR`.
And inexact elements compare the precision? And this condition would be
the same for other inexact fields?
This looks nice, but at the moment that we check the relation (in
`Expression.__nonzero__`) the conversion to `RR` has already happened.
That means we cannot use the relation to determine elementship. So we
again have special code, though it's special for inexact fields and it's
not necessary to write it for every class.
--
Ticket URL: <http://trac.sagemath.org/ticket/17984#comment:21>
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