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/8ee98f5b-0502-461f-9b6c-c7e588ed062en%40googlegroups.com.
