On May 24, 9:37 pm, luisfe <[email protected]> wrote:
> I am not sure if this is a bug or an unexpected bud valid behavior,
> since we are dealing with conversions instead of coercions.
>
> {{{
> sage: K1=PolynomialRing(QQ, 't',10, order=TermOrder('degrevlex', 4) +
> TermOrder('degrevlex', 6) )
> sage: K2=PolynomialRing(ZZ, 't',10)
> sage: [K2(f) for f in K1.gens()]
> [t6, t7, t8, t9, t2, t2, t0*t2, t1*t2, t2, t2]
>
> }}}
>
> If K2 has the same termorder as K1 I get the expected result.
>
> {{{
> sage: K2=PolynomialRing(ZZ, 't',10, order=TermOrder('degrevlex',
> 4)+TermOrder('degrevlex',6))
> sage: [K2(f) for f in K1.gens()]
> [t0, t1, t2, t3, t4, t5, t6, t7, t8, t9]
>
> }}}
After some tryings, it seems to me that non-standard term orders are
broken in the coercion model
{{{
sage: K1=PolynomialRing(QQ, ('x,y'))
sage: x,y=K1.gens()
sage: (x-y)*vector([1,2,3])
(x - y, 2*x - 2*y, 3*x - 3*y)
sage: K1=PolynomialRing(QQ, ('x,y'),order='deglex')
sage: x,y=K1.gens()
sage: (x-y)*vector([1,2,3])
---------------------------------------------------------------------------
TypeError Traceback (most recent call
last)
/home/luisfe/trabajo/algoritmos/sage/reparametrization/<ipython
console> in <module>()
/opt/SAGE/sage-devel/local/lib/python2.6/site-packages/sage/structure/
element.so in sage.structure.element.RingElement.__mul__ (sage/
structure/element.c:11449)()
/opt/SAGE/sage-devel/local/lib/python2.6/site-packages/sage/structure/
coerce.so in sage.structure.coerce.CoercionModel_cache_maps.bin_op
(sage/structure/coerce.c:6996)()
TypeError: unsupported operand parent(s) for '*': 'Multivariate
Polynomial Ring in x, y over Rational Field' and 'Ambient free module
of rank 3 over the principal ideal domain Integer Ring'
}}}
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