On Sat, Nov 28, 2009 at 3:55 PM, Stefan Boettner <[email protected]> wrote:
> William,
>
> I can factor polynomials with coefficients in QQ fine. Here are the
> examples I mentioned in greater detail:
>
> # define the coefficient field K and R=K[x,y]
> K.<a>=PolynomialRing(QQ,1)
> K=FractionField(K)
> R.<x,y>=PolynomialRing(K,2)
>
> # the following works:
> (x^2-y^2).factor()
> # answer: (x - y) * (x + y)
>
> # this one also works:
> (x^2-a^2*y^2).factor()
> # answer: (x + (-a)*y) * (x + a*y)
>
> # the following two are the simplest ones that fail:
> x.factor()
> # raises NotImplementedError
>
> R(1).factor()
> # raises IndexError: list index out of range
>
>
> If x^2-y^2 can be factored correctly, wouldn't I expect that factoring
> just x is also implemented? Maybe it's also just a bug.

Yes.

Well there is definitely a bug.  I've opened this ticket:

   http://trac.sagemath.org/sage_trac/ticket/7554

William

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