Dear all, Yesterday I ran into a problem when using the FLINT pseudo division methods in SAGE. Below I am copying part of an email I sent to Bill Hart already.
Sebastian [Bug report] While working on re-implementing QQ[] in SAGE, I came across the following inconsistency. From the FLINT 1.4.0 manual, I think the methods fmpz_poly_pseudo_divrem and fmpz_poly_pseudo_div should return the same quotient. But using the "div" method I get A = x^4-4*x^2+2*x+2 B = x-2560 Q = x^3+2560*x^2+6553596*x+3892303874 m = 0 whereas the "divrem" yields A = x^4-4*x^2+2*x+2 B = x-2560 Q = x^3+2560*x^2+6553596*x+16777205762 m = 0 The second answer is the correct one. Temporarily, I have now changed the relevant Cython code to cdef fmpz_poly_t rem fmpz_poly_init(rem) fmpz_poly_pseudo_divrem(q.num, rem, &m, a.num, b.num) fmpz_poly_clear(rem) # fmpz_poly_pseudo_div(q.num, &m, a.num, b.num) and it seems to work fine, as far as many random comparisons between the output of "f // g" with new QQ[] and with the old QQ[] suggest. Here is another example, for which the output doesn't agree: f = -10*x^6 + x^5 + 2*x^4 - x^3 + 2*x^2 - x - 1 g = 75*x^4 - 1/2*x^3 - x^2 + 37/3*x - 1/124 In case this helps, I am working with SAGE 4.1.2.alpha0 under Ubuntu 8.10. --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
