Your diagnosis makes sense, since in PARI there are no multivariate polynomials, only polys with poly coefficients.
John On 26 March 2012 02:52, Ben Hutz <bn4...@gmail.com> wrote: > The resultant of two homogeneous polynomials can return an incorrect > value: > R.<x,y>=PolynomialRing(ZZ) > f=6*x^2 + x*y + y^2 > g=y^2 > print f.resultant(g) > m=matrix([[6,1,1,0],[0,6,1,1],[0,0,1,0],[0,0,0,1]]) > m.determinant() > > notice that the coefficient of the f.resultant(g) does not match the > integer determinant (they should be the same). I believe this is > because the .resultant function is actually calling the pari library, > which is interpreting y^2 as a single variable polynomial. Thus it > builds the wrong matrix > > m=matrix([[6,1,1,0],[0,6,1,1],[1,0,0,0],[0,1,0,0]]) > m.determinant() > > which is the value Sage is returning. The correct value is returned in > Sage from > > m=f.sylvester_matrix(g,x) > m.determinant() > > Ben > > -- > To post to this group, send an email to sage-devel@googlegroups.com > To unsubscribe from this group, send an email to > sage-devel+unsubscr...@googlegroups.com > For more options, visit this group at > http://groups.google.com/group/sage-devel > URL: http://www.sagemath.org -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
