On Aug 24, 4:40 am, Kevin McGown <[EMAIL PROTECTED]> wrote:
> William,
>
> In SAGE 2.8 it seems there is a problem with the is_principal method
> for fractional ideals in a number field. In the code below I create
> the same ideal in two different ways and obtain two different answers
> from is_principal (True and False).
>
> K = QuadraticField(-119,'a')
> P2 = K.ideal([2]).factor()[0][0]
> I = P2^5
> a = K.0
> J = K.ideal([1/2*a+3/2])
> I==J
> I.is_principal()
> J.is_principal()
>
Hello Kevin,
with Sage 2.8.2 I get:
sage: K = QuadraticField(-119,'a')
sage: P2 = K.ideal([2]).factor()[0][0]
sage: I = P2^5
sage: a = K.0
sage: J = K.ideal([1/2*a+3/2])
sage: I==J
True
So, could you please test after you upgrade Sage if the problem is
gone there, too?
> I believe the problem is with the following line in the is_principal()
> method:
>
> if len (self.gens()) <= 1:
>
> Instead it should read:
>
> if len (self.gens_reduced()) <= 1:
>
> Not 100% sure, but I thought I would bring it to your attention.
>
> - Kevin
Cheers,
Michael
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