HiFactoring first and then calculating the roots of the factors (you don't need the multiplicity of the factor) worked fast for me...
Side note:In AA I noticed that most operations become much faster after a num.simplify(). But in this case the simplify operation is slow itself...
Best
Jonas
On 20.09.2016 14:22, Marc Mezzarobba wrote:
Clemens Heuberger wrote:x = polygen(QQ) equation = -960000000*x^7 + 416000000*x^6 - 66400000*x^5 + 5600000*x^4 - 280000*x^3 + 8400*x^2 - 140*x + 1 roots = equation.roots(QQbar) a_root = roots[-1][0] abs_root = abs(a_root)[...]Is this expected behaviour?Well, QQbar has a number of well-known but not yet fixed efficiency problems...I am intersted in the smallest root(s) in absolute value only, any suggestions for achieving that in less time?You could perhaps compute a polynomial whose roots include the z·conj(z) for all roots z of equation (e.g., with a resultant), factor that polynomial, and sort its root numerically while increasing the precision until you can tell which of the factors correspond to dominant roots. Or something like that :-/
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