Re: [sage-support] How can I tell if an algebraic number is rational?
PolynomialRing(ZZ, 'x') This is only an aside, but I should probably warn that (unlike var, say) this doesn't change x, so it might not do what you're thinking. x is still an Expression, an element of the Symbolic Ring, and so f is also an Expression. You probably want to use something like sage: R.x = PolynomialRing(ZZ) sage: parent(x) Univariate Polynomial Ring in x over Integer Ring sage: f=x^3 + A*x +B sage: parent(f) Univariate Polynomial Ring in x over Integer Ring or R.x = ZZ[] or something. Doug -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org
Re: [sage-support] How can I tell if an algebraic number is rational?
On Wed, Jun 1, 2011 at 7:30 AM, zsharon zacherysha...@gmail.com wrote: Hi, I need to determine if a given algebraic number is rational. Here is the setup: PolynomialRing(ZZ, 'x') A=-2 B=5 f=x^3 + A*x +B D=-4*A^3-27*B^2 L.c = NumberField(f) Then I need to know if a given number beta=b0+b1*c+b2*c^2 is rational or not. It tried using K.s=QQ.extension(beta.minpoly()) K==QQ but I'm not sure if this is reliable. To test membership, just do sage: beta in QQ - Robert -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org
