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Compute with the exact root of a polynomial : rootof

Let P and Q be two polynomials given by the list of their coefficients then rootof(P,Q) denotes the value P($ \alpha$) where $ \alpha$ is the root of Q with largest real part (and largest imaginary part in case of equality).
In exact computations, Xcas will rewrite rational evaluations of rootof as a unique rootof with degree(P) <degree(Q). If the resulting rootof is the solution of a second degree equation, it will be simplified.

Example
Let $ \alpha$ be the root with largest imaginary part of Q(x) = x4 + 10x2 + 1 (all roots of Q have real part equal to 0).


next up previous contents index
suivant: Exact roots of a monter: Polynomials précédent: Rewrite in terms of   Table des matières   Index
giac documentation written by Renée De Graeve and Bernard Parisse