Dear Waldek, thanks for the reply and apologies for being imprecise.
Actually the algebraic numbers I talk about are rational expression of nested radicals. In fact, I get all roots of a polynomial via radicalRoots $ RadicalSolvePackage(ZZ). Degree is <= 4 (mostly 2). These roots undergo some rational operation and multiplication with other roots. But let's forget about the latter. I am actually talking about all roots.
I know that I can find rational intervals for all real roots as tight as I want them. I basically need a matching of these intervals with the respective radical expressions that I get from radicalRoots.
Additionally, given an algebraic number z, it would be great if FriCAS had a way to find a p \in Z[x] such that p(z)=0 (minimal poly for z). I looked at definingPolynomial and it is not so helpful, as I would have to construct the minimal polynomial over QQ myself.
I guess, a function AlgebraicNumber -> RealClosure(QQ) is not reliable, because AlgebraicNumber does not encode which of the roots of the minimal polynomial is actually meant, i.e. I cannot even say whether
sqrt(2)@AN is positive. (Oh, yes, I know that AN does not export <.) Ralf -- You received this message because you are subscribed to the Google Groups "FriCAS - computer algebra system" group. To unsubscribe from this group and stop receiving emails from it, send an email to fricas-devel+unsubscr...@googlegroups.com. To view this discussion visit https://groups.google.com/d/msgid/fricas-devel/c51a85c0-25bc-4e1d-8b38-00999854c49b%40hemmecke.org.
