jacobian(L: LIST of RINGELEM): MAT
/**/ Use R ::= QQ[x,y]; /**/ L := [x-y, x^2-y, x^3-y^2]; /**/ jacobian(L); matrix( /*RingDistrMPolyClean(QQ, 2)*/ [[1, -1], [2*x, -1], [3*x^2, -2*y]])