In UnivariatePolynomialCategory: if R has CommutativeRing then discriminant : % -> R resultant : (%, %) -> R
However, in SparseUnivariatePolynomial: if R has IntegralDomain then discriminant(p) == discriminant(p)$PseudoRemainderSequence(R, %) resultant(p1, p2) == resultant(p1, p2)$PseudoRemainderSequence(R, %) So discriminant and resultant are not defined for domains that are COMRING but not INTDOM, for example IntegerMod 6. The resultant can be solved easily: In BezoutMatrix, I recently added subResultant which computes resultant by determinant of Sylvester matrix. subResultant(p, q, 0) = resultant(p, q) So we can add function resultant in BezoutMatrix, and in SUP, redirect to BezoutMatrix when coefficients are COMRING but not INTDOM. As for discriminant, wikipedia says it can be computed by take determinant of Sylvester matrix with first column replaced by 1: https://en.wikipedia.org/wiki/Discriminant#Discriminant_of_a_polynomial_over_a_commutative_ring My concerns are performance, the determinant method is very slow compared with pseudo division, but I think there's no better algorithm for COMRING? If so, I'll start implementing such functions in bezout.spad and poly.spad. -- You received this message because you are subscribed to the Google Groups "FriCAS - computer algebra system" group. To unsubscribe from this group and stop receiving emails from it, send an email to fricas-devel+unsubscr...@googlegroups.com. To post to this group, send email to fricas-devel@googlegroups.com. Visit this group at https://groups.google.com/group/fricas-devel. For more options, visit https://groups.google.com/d/optout.