#16934: Finite fields coercion bug
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Reporter: jdemeyer | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-6.4
Component: coercion | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Description changed by jdemeyer:
Old description:
> The following sequence of commands somehow breaks the coercion framework.
> This is on vanilla Sage 6.4.beta1. The problem only occurs if
> {{{impl="pari_ffelt"}}} is explicitly given, even though that is the
> default:
> {{{
> sage: k.<a> = GF(17^14, impl="pari_ffelt")
> sage: _ = EllipticCurve_from_j(a^584645231109031).cardinality()
> sage: k.<a> = GF(17^14, impl="pari_ffelt")
> sage: _ = EllipticCurve_from_j(a^584645231109031).cardinality()
> TypeError Traceback (most recent call
> last)
> [...]
> TypeError: no coercion defined
> }}}
>
> Remark: the value `a^584645231109031` is chosen to lie in the subfield
> `GF(17^2)`, an elliptic curve over this field is created in the
> `cardinality()` call.
New description:
The following sequence of commands somehow breaks the coercion framework.
This is on vanilla Sage 6.4.beta1. The problem only occurs if
{{{impl="pari_ffelt"}}} is explicitly given, even though that is the
default:
{{{
sage: k.<a> = GF(17^14, impl="pari_ffelt")
sage: _ = EllipticCurve_from_j(a^584645231109031).cardinality()
sage: k.<a> = GF(17^14, impl="pari_ffelt")
sage: E = EllipticCurve_from_j(a^584645231109031)
TypeError Traceback (most recent call
last)
[...]
TypeError: no coercion defined
}}}
Remark: the value `a^584645231109031` is chosen to lie in the subfield
`GF(17^2)`, an elliptic curve over this field is created in the
`cardinality()` call.
--
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Ticket URL: <http://trac.sagemath.org/ticket/16934#comment:1>
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