#14982: When a parent is equipped with an embedding, consider coercions that
don't
go through the embedding
-------------------------------------+-------------------------------------
Reporter: mmezzarobba | Owner:
Type: defect | Status: needs_review
Priority: major | Milestone: sage-6.4
Component: coercion | Resolution:
Keywords: embedding | Merged in:
Authors: Marc Mezzarobba | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/mmezzarobba/14982-coerce_embeddings|
4b55415e1dd476e6010fb82b174d5fa455f963bd
Dependencies: | Stopgaps:
-------------------------------------+-------------------------------------
Comment (by mmezzarobba):
Replying to [comment:46 vdelecroix]:
> I fixed the `q_binomial` issue (see the commit on top `public/14982`,
WARNING: it is merged with 6.7.beta2).
Thanks, your fix is much better than what I did (even though the
particular issue would probably have been solved by the ticket about `I`).
Just one question: why are you doing
{{{
try:
zero = R.zero()
except AttributeError:
zero = R(0)
try:
one = R.one()
except AttributeError:
one = R(1)
}}}
instead of just
{{{
zero = R(0)
one = R(1)
}}}
(Are there cases where `R.zero()` would work but not `R(0)`? Or is it
faster that way when `R` is a `Parent`, despite the `try`/`catch` block?
And then, does speed matter?)
> If you like it just cherry-pick it on top of your branch.
I guess I will even rebase the whole thing and merge related commits when
we're done talking about it.
> I actually found another bug:
> {{{
> sage: Sym = SymmetricFunctions(QQ)
> sage: s = Sym.schur()
> sage: 1 - s[2]
> s[] - s[2]
> sage: 1r - s[2]
> Traceback (most recent call last):
> ...
> TypeError: unsupported operand type(s) for -: 'int' and
> 'SymmetricFunctionAlgebra_schur_with_category.element_class'
> }}}
But this example already didn't work before this ticket, did it?
--
Ticket URL: <http://trac.sagemath.org/ticket/14982#comment:48>
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