#18529: Topological manifolds: basics
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Reporter: egourgoulhon | Owner: egourgoulhon
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-6.10
Component: geometry | Resolution:
Keywords: topological | Merged in:
manifolds | Reviewers:
Authors: Eric Gourgoulhon | Work issues:
Report Upstream: N/A | Commit:
Branch: | 252e616cc053a3b76ee563282222507cd78c9fb8
public/manifolds/top_manif_basics | Stopgaps:
Dependencies: #18175 |
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Comment (by egourgoulhon):
Replying to [comment:27 tscrim]:
>
> - I don't quite agree with checking `self._field == RR` for real charts
as the precision should not matter. I would check `isinstance(self._field,
RealField)` instead. Granted, we probably should have a function that
checks against all known real field implementations...
>
> - In a similar vein, I don't like the input of `'real'` to `RR` (and
`'complex'` to `CC`). I would make the user be explicit about what they
want unless you are doing to do some special handling to make this pass
special arguments to an underlying `SR` implementation.
Actually, the precision is not used in the current setting, so neither
`RR` nor `RealField` is really necessary. `RR` was used as a substitute
for the true real field, which cannot be represented in the computer.
Looking further, why not using Sage's `RealLazyField` for this? It seems
that it is intended to be closer to the true '''R'''. One drawback is that
we have (for the moment)
{{{
sage: RLF in Fields().Topological()
False
}}}
So `RLF` cannot be passed to the manifold constructor.
The same considerations apply of course to `ComplexLazyField`.
--
Ticket URL: <http://trac.sagemath.org/ticket/18529#comment:53>
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