h.resul

强大的数学工具包

                               * * * * * * *
                               *   resul   *
                               * * * * * * *

        "resultant"
        SYNTAX: X = resul(f, g, x, alg)

        f and g are expressions whose values are polynomials over Z, 
        Z/pZ (where p is a prime) or GF(p^n) (where p is a prime > 2).
        x is a variable.
        alg is 1, 2, 3 or 4.

        X is assigned the resultant of f and g with respect to the
        variable x. X is computed according to the following algorithms:

        If P is a polynomial over Z:
        the algorithm of Sylvester,             if alg = 1,
        the algorithm of Bezout,                if alg = 2,
                 (Warning: X is only exact up to sign!)
        the algorithm of Collins-Sylvester,     if alg = 3,
        the algorithm of Collins,               if alg = 4.

        If P is a polynomial over Z/pZ:
        the algorithm of Sylvester,             if alg = 1,
        the algorithm of Bezout,                if alg = 2,
                 (Warning: X is only exact up to sign!)
        the algorithm of Collins,               if alg = 3 or 4.

        If P is a polynomial over GF(p^n):
        the algorithm of Sylvester in every case.

        Warning: If p > 2^30, the primality of p is not tested.


        Example 1: (correct)

                resul(x*y + y, x + 1, x, 2)


        Example 2: (incorrect)

                resul(1/7*x + 1, x^2, x, 3)
                
_ERR_NR_037


        Example 3: (incorrect)

                resul(x^2 + 1, x^2 + 2, y, -4)
                
_ERR_NR_035