Re: [sage-devel] (x^6+y^9)%(x^3-y^2-1) == x^12*y - 4*x^9*y + ...

2023-03-09 Thread Dima Pasechnik
On Thu, Mar 9, 2023 at 5:29 PM G. M.-S. wrote: > > > Could you elaborate, Dima? > > It seems to me that quo_rem ignores the ordering and always uses invlex. Sorry, I was not thinking clearly. In fact, I think, '%' shoud work for ideals on the right-hand side, not just for polynomials (i.e.

Re: [sage-devel] (x^6+y^9)%(x^3-y^2-1) == x^12*y - 4*x^9*y + ...

2023-03-09 Thread G. M.-S.
Could you elaborate, Dima? It seems to me that *quo_rem* ignores the ordering and always uses *invlex*. Would this be a bug or a feature? Guillermo On Thu, 9 Mar 2023 at 17:45, Dima Pasechnik wrote: > On Thu, Mar 9, 2023 at 2:07 PM G. M.-S. wrote: > > > > > > John is right. > > > > Dividing

Re: [sage-devel] (x^6+y^9)%(x^3-y^2-1) == x^12*y - 4*x^9*y + ...

2023-03-09 Thread Dima Pasechnik
On Thu, Mar 9, 2023 at 2:07 PM G. M.-S. wrote: > > > John is right. > > Dividing a by b means finding q and r such that a = q*b + r and r is either 0 > or "smaller" than b. > The question is the meaning of "smaller". > > For univariate polynomials, one says that r is smaller than b if deg(r) <

Re: [sage-devel] (x^6+y^9)%(x^3-y^2-1) == x^12*y - 4*x^9*y + ...

2023-03-09 Thread G. M.-S.
John is right. Dividing a by b means finding q and r such that a = q*b + r and r is either 0 or "smaller" than b. The question is the meaning of "smaller". For univariate polynomials, one says that r is smaller than b if deg(r) < deg(b) (one can include r = 0 by defining deg(0) = –∞). For

Re: [sage-devel] (x^6+y^9)%(x^3-y^2-1) == x^12*y - 4*x^9*y + ...

2023-03-09 Thread John Cremona
Surely it is just a question of precedence of variables. In Sage you are dividing by a quadratic in y and getting a remainder which is linear in y. In pari you are dividing by a cubic in x and getting a remainder which is of degree <3 in x. If you swap x and y in both polynomials, sage's

[sage-devel] (x^6+y^9)%(x^3-y^2-1) == x^12*y - 4*x^9*y + ...

2023-03-09 Thread Georgi Guninski
Is this a bug: sage: K.=QQ[] sage: (x^6+y^9)%(x^3-y^2-1) x^12*y - 4*x^9*y + 6*x^6*y + x^6 - 4*x^3*y + y In pari: ? (x^6+y^9)%(x^3-y^2-1) %1 = y^9 + y^4 + 2*y^2 + 1 -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group