pcoeff (or pcoef) takes as argument a list of
the roots of a polynomial P.
pcoeff (or pcoef) returns a univariate polynomial having
these roots,
represented as the list of its coefficients by decreasing order.
Input :
Output :
i.e. (x−1)(x−2)(x2)(x−3)=x5−6x4+11x3−6x2.