`res'
-----

res(VAR,POLY1,POLY2[,MOD])
     :: Resultant of POLY1 and POLY2 with respect to VAR.

RETURN
     polynomial

VAR
     indeterminate

POLY1 POLY2
     polynomial

MOD
     prime

   * Resultant of two polynomials POLY1 and POLY2 with respect to VAR.

   * Sub-resultant algorithm is used to compute the resultant.

   * The computation is done over GF(MOD) if MOD is specified.

     [0] res(t,(t^3+1)*x+1,(t^3+1)*y+t);
     -x^3-x^2-y^3

