Thanks, Anton -- I have forwarded to sage-devel and flint-devel and we'll try to get this fixed before the release of 6.5.
John Cremona On 16 February 2015 at 23:54, Anton Mellit <[email protected]> wrote: > Here is the code: > R.<q>=QQ[] > X=3*q^12 - 8*q^11 - 24*q^10 - 48*q^9 - 84*q^8 - 92*q^7 - 92*q^6 - 70*q^5 - > 50*q^4 - 27*q^3 - 13*q^2 - 4*q - 1 > Y=q^13 - 2*q^12 + 2*q^10 - q^9 > print gcd(X,Y) > print X(1) > Here is the output: > q - 1 -510 > The bug is extremely serious because it affects all computations with > rational functions. It is also quite rare, I believe. I traced it down to > the function _fmpz_poly_gcd_heuristic in FLINT. The bug is triggered when > the heuristic algorithm fails, one of the divisibility checks fails, but > still the value is returned as o.k. > The fix is easy, just one line needs to be added > if (divides) /* quotient really was exact */ { --->>>>> divides=0; > > -- > You received this message because you are subscribed to the Google Groups > "sage-support" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/sage-support. > For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/d/optout.
