Ahh ok, thank you. Considering the following output I think a PR to make the degree of zero for these Laurent classes -Infinity is reasonable?
``` sage: R.<x> = LaurentSeriesRing(QQ) sage: R.zero().valuation() +Infinity sage: R.zero().degree() -1 sage: sage: R.<x> = LaurentPolynomialRing(QQ) sage: R.zero().valuation() +Infinity sage: R.zero().degree() -1 sage: sage: R.<x> = LazyLaurentSeriesRing(QQ) sage: R.zero().valuation() +Infinity sage: R.zero().degree() # Errors On Wednesday, February 28, 2024 at 1:50:23 PM UTC Martin R wrote: > 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/1d06c246-f250-4c37-997e-066ddaefbaean%40googlegroups.com.
