On Nov 25, 7:15 pm, Alex Raichev <[EMAIL PROTECTED]> wrote:
> Hi all:
Hi Alex,
> Do any of you know what is going wrong with the variety() command in
> the example below? Sometimes it works, and sometimes it doesn't. The
> problem seems to be variety()'s call to triangular_decomposition().
>
> Alex
>
> ----------------------------------------------------------------------
> | Sage Version 3.2, Release Date: 2008-11-20 |
> | Type notebook() for the GUI, and license() for information. |
> ----------------------------------------------------------------------
>
> sage: R.<w,z>= PolynomialRing(QQ,2,order='lex')
> sage: F= 19 -20*z -20*w +5*z^2 +14*z*w +5*w^2 -2*z^2*w -2*z*w^2
> +z^2*w^2
> sage: G= (w*z-1)*F
> sage: for f in [F,G]:
> ....: I= ideal([f] +f.gradient())
> ....: I= ideal(I.groebner_basis())
> ....: print I
> ....: I.vector_space_dimension()
> ....: I.variety()
> ....:
> Ideal (w - 1, z - 1) of Multivariate Polynomial Ring in w, z over
> Rational Field
> 1
> [{z: 1, w: 1}]
> Ideal (w^2 - 2*w - 17/5*z^4 + 434/25*z^3 - 817/25*z^2 + 672/25*z -
> 179/25, w*z - w + 33/28*z^4 - 433/70*z^3 + 869/70*z^2 - 839/70*z +
> 641/140, z^5 - 27/5*z^4 + 56/5*z^3 - 56/5*z^2 + 27/5*z - 1) of
> Multivariate Polynomial Ring in w, z over Rational Field
> 6
Is this reproducible for you every time? It might be an issue inside
Singular, a pexpect synchronization issue or just a plain old bug in
Sage. Our Singular expert (Martin Albrecht) has a bad net connection
the next couple days, so if I can reproduce this I will open a ticket.
Cheers,
Micheal
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