From: "Fred lunnon" <fred.lunnon@gmail.com>
Hmmm. John Cannon reported that his 2.4GHz Opteron took 0.9 sec to find B(2999) using the Magma transcription of my implementation. At a rough guess, this would scale down at most 0.05 sec for B(1000) ...
Here is the related part of William Stein's post in sage-devel: -------------------Start of the (edited) quote------------------ On 7/24/07, Jack Schmidt <Jack.Schmidt.SciMath@gmail.com> wrote:
GAP takes under a second to compute Bell(1000), compared to over a minute (and going) for maple on the same computer.
Gap takes about 1 second for this on one of my test machines. Nick Alexander wrote an optimized native SAGE function that computes *all* bell numbers up to n very quickly, much more quickly than Gap computes even one! sage: time v=expnums(1001,1) # this computes *all* Bell numbers up to Bell(1000) CPU times: user 0.12 s, sys: 0.00 s, total: 0.12 s Wall time: 0.13 sage: v[1000] == bell_number(1000) # uses GAP; about a second True sage: v[990] == bell_number(990) True sage: time v=expnums(2000,1) CPU times: user 1.36 s, sys: 0.04 s, total: 1.40 s Wall time: 2.35 How do you compute BellB in Mathematica? I get In[2]:= BellB[1000] Out[2]= BellB[1000] -- William -- William Stein Associate Professor of Mathematics University of Washington http://www.williamstein.org -----------------------End of (edited) quote------------------- Alec