Re : how to handle roots of unity symbolically ?

On 2012-11-23, Robert Dodier <robert.dodier <at> gmail.com> wrote:
>On 2012-11-22, Roberto Fernandez <rfz <at> free.fr> wrote:
>> I'm trying to simplify expressions with W being a root of unity.
>> so that : W^n = 1
>
>Maybe tellrat is the function you want. I don't know much about it.

thanks for your answer,
but I've not had luck with it :(

if I give it several polynomial of the save variable as input, it takes only the last one.

(%i1) tellrat(w^6-1,w^4+w^2+1,w^3+1);
(%o1) [w^3+1]

and giving it w^n-1 as argument doesn't solve my problem

(%i1) tellrat(w^6-1);
(%o1) [w^6-1]
(%i2) ev(ratsimp(w^6-1), algebraic);
(%o2) 0
(%i3) ev(ratsimp(w^5+w^4+w^3+w^2+w+1), algebraic);
(%o3) w^5+w^4+w^3+w^2+w+1

when I expected 0 for (%o3)