On Mon, Nov 3, 2008 at 1:32 PM, Martin Rubey wrote:
>
> "Bill Page" <[EMAIL PROTECTED]> writes:
>
>> As I understand it AlgebraicNumber is supposed to be able to
>> properly order the roots.
>
> No, that's RECLOS.
>
> Unfortunately, there is no coercion from AN to RECLOS, and this would
> actually be tricky, since sqrt(-3) is not allowed in RECLOS.
>
Thanks Martin, that was a very useful reference. Actually it turns out
that RealClosure is pretty cool.
Thank you Renaud!
(1) -> P:=p^3-p+1/10
3 1
(1) p - p + --
10
Type: Polynomial Fraction Integer
(2) -> S:=select(positive?,allRootsOf(P)$RealClosure(Fraction Integer))
(2) [%A36,%A37]
Type: List RealClosure Fraction Integer
(3) -> approximate(S.1,1/10^20)::Float
(3) 0.1010312578 8101081769
Type: Float
(4) -> eval(P,p=%)
(4) 0.3 E -20
Type: Polynomial Float
(5) -> approximate(S.2,1/10^20)::Float
(5) 0.9456492739 2359144347
Type: Float
(6) -> eval(P,p=%)
(6) 0.1 E -20
Type: Polynomial Float
----
Regards,
Bill Page.
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