Sorry, I confused it with valuation, but I guess it is still a related question. On Wednesday 28 February 2024 at 14:36:35 UTC+1 Giacomo Pope wrote:
> This is not what I see on the current beta: > > sage: R.<x> = LaurentSeriesRing(QQ) > sage: R.zero().degree() > -1 > sage: R.<x> = LazyLaurentSeriesRing(QQ) > sage: R.zero().degree() > --------------------------------------------------------------------------- > AttributeError Traceback (most recent call last) > Cell In[4], line 1 > ----> 1 R.zero().degree() > > File ~/sage/sage/src/sage/structure/element.pyx:489, in > sage.structure.element.Element.__getattr__() > 487 AttributeError: > 'LeftZeroSemigroup_with_category.element_class' object has no attribute > 'blah_blah'... > 488 """ > --> 489 return self.getattr_from_category(name) > 490 > 491 cdef getattr_from_category(self, name) noexcept: > > File ~/sage/sage/src/sage/structure/element.pyx:502, in > sage.structure.element.Element.getattr_from_category() > 500 else: > 501 cls = P._abstract_element_class > --> 502 return getattr_from_other_class(self, cls, name) > 503 > 504 def __dir__(self): > > File ~/sage/sage/src/sage/cpython/getattr.pyx:357, in > sage.cpython.getattr.getattr_from_other_class() > 355 dummy_error_message.cls = type(self) > 356 dummy_error_message.name = name > --> 357 raise AttributeError(dummy_error_message) > 358 cdef PyObject* attr = instance_getattr(cls, name) > 359 if attr is NULL: > > AttributeError: 'LazyLaurentSeriesRing_with_category.element_class' object > has no attribute 'degree' > > On Wednesday, February 28, 2024 at 12:05:32 PM UTC Martin R wrote: > >> LazyLaurentSeriesRing(QQ) currently gives +Infinity. >> >> On Wednesday 28 February 2024 at 12:50:45 UTC+1 Giacomo Pope wrote: >> >>> While chasing various bugs which appeared in the CI, I ended up adding a >>> small method for computing random elements for the LaurentPolynomialRing >>> class. >>> >>> When writing randomised testing I got myself confused about the degree >>> of the zero polynomial. For the univariate and multivariate polynomial >>> rings, we currently use that the degree for 0 (both R(0).degree() as well >>> as R(0).degree(x)) is -1. This is unambiguous for the case of these types. >>> >>> However for the LaurentPolynomialRings, a polynomial with negative >>> valuation is very natural. For example the following code snippet shows the >>> ambiguity. >>> >>> sage: L.<x> = LaurentPolynomialRing(QQ) >>> sage: f = (1/x); f >>> x^-1 >>> sage: f.degree() >>> -1 >>> sage: L.zero().degree() >>> -1 >>> >>> I don't feel familiar enough with the mathematics here and the usual use >>> cases in sage to offer a PR "fixing" this, or whether it even needs fixing. >>> However, I got confused so I thought maybe others might get confused and >>> someone on this list might have a suggestion. >>> >>> I think the "usual" suggestion would be to have the degree as -infty, >>> but then there's a question about whether this should be done for other >>> polynomial rings... >>> >>> I made an issue for this on GitHub too: >>> >>> https://github.com/sagemath/sage/issues/37491 >>> >> -- 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 view this discussion on the web visit https://groups.google.com/d/msgid/sage-devel/c9c805f9-fbd0-4591-8729-002f3ad90fa1n%40googlegroups.com.
