#10897: better error msg in AlgebraicConverter.symbolic() and elsewhere
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Reporter: rbeezer | Owner: robertwb
Type: defect | Status: needs_work
Priority: minor | Milestone: sage-6.3
Component: symbolics | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Old description:
> Original summary by reporter: sqrt() as scalar multiple of QQbar vector
> {{{
> sage: QQbar(sqrt(2))*vector(QQbar, [1,2])
> (1.414213562373095?, 2.828427124746190?)
>
> sage: vector(QQbar, [sqrt(2), 2*sqrt(2)])
> (1.414213562373095?, 2.828427124746190?)
>
> sage: sqrt(2)*vector(QQbar, [1,2])
> <BOOM>
> }}}
>
> It seems sqrt() generally gets treated right as an element of QQbar, but
> as a scalar multiple of a vector over QQbar, it does not.
New description:
Original summary by reporter: sqrt() as scalar multiple of QQbar vector
{{{
sage: QQbar(sqrt(2))*vector(QQbar, [1,2])
(1.414213562373095?, 2.828427124746190?)
sage: vector(QQbar, [sqrt(2), 2*sqrt(2)])
(1.414213562373095?, 2.828427124746190?)
sage: sqrt(2)*vector(QQbar, [1,2])
...
NotImplementedError: symbol
}}}
This error is confusing: it suggests that the last example is supposed to
work, which currently is not the case.
--
Comment (by mmezzarobba):
Replying to [comment:4 rws]:
> A more informative error message would be a minimum improvement.
True.
> I could imagine subclassing the symbolic ring e.g. by creating an
AlgebraicSymbolicRing whose elements then could be coerced might be a way
to improve the situation.
Yes, perhaps. At least this is something to keep in mind if one tries to
implement a "field of constant symbolic expression" as recently discussed
on sage-devel. But I'm not sure it is worth the effort...
--
Ticket URL: <http://trac.sagemath.org/ticket/10897#comment:5>
Sage <http://www.sagemath.org>
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