#12967: bugs in comparisons between constants, wrapped pyobjects, infinity
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Reporter: dkrenn | Owner: burcin
Type: defect | Status: needs_work
Priority: major | Milestone: sage-6.6
Component: symbolics | Resolution:
Keywords: compare pi | Merged in:
infinity bool | Reviewers: Karl-Dieter Crisman
Authors: Travis Scrimshaw, | Work issues:
Ralf Stephan | Commit:
Report Upstream: N/A | c5845f6b18d582807dafaaf60ad6a5c8017173f3
Branch: u/rws/12967-2 | Stopgaps:
Dependencies: #17984 |
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Comment (by pbruin):
Replying to [comment:51 rws]:
> Replying to [comment:48 pbruin]:
> > ... What you propose sounds rather ad hoc; if we need a special
method for `RR`, then we would also need special cases for other inexact
rings like `CC`, ''p''-adic rings and power series rings...
> Bug fixing is always ad hoc.
Not at all; I often find that a good first step towards fundamentally
fixing a bug is trying to ''remove'' hacks that someone else put in to
make a specific example work.
> You can only make it easier (but by a huge amount) with good design and
a well thought out model. Since no good model presents itself and
delegating the task to the item is good design this would be an ansatz.
I disagree that no good model presents itself; defining `x in P` as
`bool(P(x) == x)` seems like a good programming model to me, since it is
simple and predictable.
The more I think about it, the more the fundamental problem does not seem
to be membership testing, but ''comparison'' between real numbers defined
in different approximations of the real numbers. Do we want `RR(sqrt(2))`
to be equal to `SR(sqrt(2))` or not? And what about `RR(1/3)` and
`QQ(1/3)`?
--
Ticket URL: <http://trac.sagemath.org/ticket/12967#comment:53>
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