On Friday 22 May 2009, simon.k...@uni-jena.de wrote:
> Hi,
>
> On 22 Mai, 02:29, Kwankyu <ekwan...@gmail.com> wrote:
> ...
>
> > This seems to me a bug. Isn't it? I am using Sage 3.4.2.
>
> Or at least: It is a very nasty inconsistency -- and note that the
> inconsistent behaviour apparently is intended.
> At least, it is doc tested:
> In the univariate case, we have the doc test
> sage: R.<x> = QQ[]
> sage: R(0).degree()
> -1
> and in the multivariate case, we have the doc test
> sage: P.<x, y> = QQ[]
> sage: P(0).degree(x)
> 0
> sage: P(1).degree(x)
> 0
This is just me being stupid (or at least I was stupid when I wrote this). It
should definitely be -1. Note that I hardcoded the zero:
if self._poly == NULL:
return 0
I'll open a ticket and provide a fix.
> I think that it is quite usual to say that the zero polynomial has
> *no* degree, while all other constant polynomials have degree 0. And
> "no degree" is often accomplished by returning -1. This is done, e.g.,
>
> in Singular:
> > ring R = 0, (x,y), dp;
> > deg(0);
>
> -1
>
> My vote:
> +1 for -1
>
>
> While we are at it:
> sage: Q=singular.ring(0,'(x,y)','dp')
> sage: Q(0)
> -> boom
>
> I think the __call__ method of *all* rings (including those rings
> defined via some interface) should do essentially the same: Try to
> interprete the arguments as a ring element.
We just don't have any special code for Singular rings so all that is needed
is a patch which adds it ;)
Martin
--
name: Martin Albrecht
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