Hi Enrique, On 2015-02-19, Enrique Artal <enriquear...@gmail.com> wrote: >> > This is not really an issue, the problem is the fact that the=20 >> function=20 >> > accept the entry *order* but it ignores it silently.=20 >> >> Ahm, why do you think it is ignored?=20 >> > I have rechecked that =20 > *R.<t>=3DPolynomialRing(QQ,order=3D'neglex');(1+t).is_unit()* yields False
The problem here is that you are constructing a univariate polynomial ring, for which Sage does not use Singular. If you want to use different term orderings or a localisation, you should construct a "multivariate polynomial ring with a single variable" (I know, this it sounds silly and is not obvious). To do so, you should not only provide the list of generator names (this is what you implicitly do when you write "R.<t> = ..."), but also the number of generators. Hence: sage: R.<t> = PolynomialRing(QQ, 1, order='negdeglex') sage: R # Note: It is MULTIvariate Multivariate Polynomial Ring in t over Rational Field sage: R.term_order() Negative degree lexicographic term order sage: (1+t).is_unit() True in contrast to sage: R.<t> = PolynomialRing(QQ, order='negdeglex') sage: R # Note: It is UNIvariate Univariate Polynomial Ring in t over Rational Field sage: R.term_order() Traceback (most recent call last): ... AttributeError: ... Same for "neglex" (I actually didn't know that this exists, it is not mentioned in the docstring): sage: R.<t> = PolynomialRing(QQ, 1, order='neglex') sage: R.term_order() Negative lexicographic term order sage: (1+t).is_unit() True Best regards, Simon -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at http://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
