Bill Allombert on Sun, 28 Oct 2012 23:52:51 +0100


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Re: charpoly via Newton


On Wed, Oct 24, 2012 at 02:01:14PM +0200, Pascal Molin wrote:
> polcomposed(P,Q) = prod_{P(a)=Q(b)=0} (x-ab)

For this one, you can use polresultant:
polcomposed(P,Q) = polresultant(subst(P,'x,'y/'x)*'x^poldegree(P),Q,'x);

Cheers,
Bill.