#11904: Change default variable name for NumberFieldElement -> PARI conversion
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Reporter: jdemeyer | Owner: davidloeffler
Type: defect | Status: new
Priority: major | Milestone: sage-4.7.2
Component: number fields | Keywords:
Work_issues: | Upstream: N/A
Reviewer: | Author:
Merged: | Dependencies: #11891
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Description changed by jdemeyer:
Old description:
> Currently, we get:
> {{{
> sage: K.<a> = NumberField(x^3 + 2)
> sage: (a + 2)._pari_()
> Mod(x + 2, x^3 + 2)
> }}}
> Note that the variable `x` is used. Since polynomials prefer the variable
> name `x`, it might be better to use `y` by default (or any other name)
> for number field elements.
>
> Also, the `_pari_()` methods for `NumberFieldElement_absolute` and
> `NumberFieldElement_relative` are exactly the same, so we should avoid
> code duplication.
New description:
This should be fixed:
{{{
sage: K.<a> = NumberField(x^3 + 2)
sage: R.<x> = PolynomialRing(K)
sage: pari(a*x)
---------------------------------------------------------------------------
PariError Traceback (most recent call
last)
/usr/local/src/sage-4.7.2.alpha2/<ipython console> in <module>()
/usr/local/src/sage-4.7.2.alpha2/local/lib/python2.6/site-
packages/sage/libs/pari/gen.so in sage.libs.pari.gen.PariInstance.__call__
(sage/libs/pari/gen.c:43353)()
/usr/local/src/sage-4.7.2.alpha2/local/lib/python2.6/site-
packages/sage/rings/polynomial/polynomial_element.so in
sage.rings.polynomial.polynomial_element.Polynomial._pari_
(sage/rings/polynomial/polynomial_element.c:27815)()
/usr/local/src/sage-4.7.2.alpha2/local/lib/python2.6/site-
packages/sage/rings/polynomial/polynomial_element.so in
sage.rings.polynomial.polynomial_element.Polynomial._pari_with_name
(sage/rings/polynomial/polynomial_element.c:28109)()
/usr/local/src/sage-4.7.2.alpha2/local/lib/python2.6/site-
packages/sage/libs/pari/gen.so in sage.libs.pari.gen._pari_trap
(sage/libs/pari/gen.c:48151)()
PariError: (5)
}}}
The reason is:
{{{
sage: K.<a> = NumberField(x^3 + 2)
sage: a._pari_()
Mod(x, x^3 + 2)
}}}
Note that the variable `x` is used. Since polynomials prefer the variable
name `x`, it might be better to use `y` by default (or any other name) for
number field elements.
Also, the `_pari_()` methods for `NumberFieldElement_absolute` and
`NumberFieldElement_relative` are exactly the same, so we should avoid
code duplication.
--
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11904#comment:1>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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