Re, I've noticed that the slowness is actually also function of the number of terms, in a surprising way:
sage: R.<x> = PolynomialRing(ZZ,sparse=True) sage: S.<y> = PolynomialRing(ZZ,implementation="FLINT") sage: f = x^100000 sage: %time _ = S(f) CPU times: user 8.71 s, sys: 2.84 ms, total: 8.72 s Wall time: 8.72 s sage: f = x^100000 + R.random_element(99999) sage: %time _ = S(f) CPU times: user 34.4 ms, sys: 8.08 ms, total: 42.4 ms Wall time: 37.4 ms sage: f = R.random_element(100).subs(x=x^1000) sage: %time _ = S(f) CPU times: user 141 ms, sys: 0 ns, total: 141 ms Wall time: 141 ms I am still unable to find where it comes from! Cheers, Bruno Le samedi 13 décembre 2014 16:05:09 UTC+1, Bruno Grenet a écrit : > > Working on ticket #15790 <http://trac.sagemath.org/ticket/15790>,¹ I've > noticed that coercion from Sparse Polynomial Ring over ZZ to Dense > Polynomial over ZZ with FLINT implementation is unexpectedly slow. It is > not the case with the NTL implementation, and it is actually not the case > either if we do not do coercion but simply define the same polynomial > directly: > > sage: R.<x> = PolynomialRing(ZZ,sparse=True) > sage: S.<y> = PolynomialRing(ZZ,implementation="FLINT") > sage: T.<z> = PolynomialRing(ZZ,implementation="NTL") > sage: f=x^100000 > > sage: %time S(f) # Coercion, with FLINT > CPU times: user 8.83 s, sys: 96 ms, total: 8.92 s > Wall time: 8.94 s > y^100000 > > sage: %time T(f) # Coercion, with NTL > CPU times: user 32.1 ms, sys: 0 ns, total: 32.1 ms > Wall time: 32.1 ms > z^100000 > > sage: %time _= y^100000 # Direct input, with FLINT > CPU times: user 624 µs, sys: 4 µs, total: 628 µs > Wall time: 637 µs > > Despite the fact that this is way faster with NTL, the time complexity > seems to be linear with NTL and quadratic with FLINT. > > I haven't found where it may come from! > Cheers, > Bruno > > ¹ Btw, the ticket is ready to review, as well as #16516 > <http://trac.sagemath.org/ticket/16516>. ;-) > -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at http://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
