On Thu, Jan 15, 2009 at 4:10 PM, <[email protected]> wrote:
> That's interesting because I calculated M
> 37 = 2^3021377-1 (909526 digits) on a 2.6 GHz pentium 4 using my own C++
> class to represent large ints and it about 2 hours.
>
> I calculated the same thing on www.sagenb.org and it took about 6 minutes!
>
> Well, I suppose 4 Xeon cores is a mini cluster of sorts.
That doesn't matter, since Sage's code for doing integer arithmetic
doesn't take advantage of multiple cores. It's only doing that using
one core. When you write "my own C++ class to represent large ints",
this suggests that you're using an entirely different algorithm than
Sage to do arithmetic with large integers.
Computing M with Sage takes less than *one second* for me on sagenb.org:
sage: time s = 2^3021377-1
CPU time: 0.00 s, Wall time: 0.00 s
sage: time k = str(s)
CPU time: 0.67 s, Wall time: 0.67 s
The same computation on some other new hardware I recently got from
Sun with big caches is even faster:
sage: time s = 2^3021377-1
CPU times: user 0.00 s, sys: 0.00 s, total: 0.00 s
Wall time: 0.00 s
sage: time k = str(s)
CPU times: user 0.40 s, sys: 0.01 s, total: 0.41 s
Wall time: 0.41 s
sage: len(k)
909526
sage: timeit('s = 2^3021377-1')
625 loops, best of 3: 83.3 µs per loop
Why don't you try using Sage on your 2.6Ghz Pentium 4 to do the computation?
>
> Regards,
> A. Jorge Garcia
>
> Teacher & Professor
> Applied Mathematics, Physics & Computer Science
> Baldwin Senior High School & Nassau Community College
>
> [email protected]
> http://calcpage.tripod.com
> ftp://centauri.baldwinschools.net
>
>
>
>
> ________________________________
> A Good Credit Score is 700 or Above. See yours in just 2 easy steps!
> >
>
--
William Stein
Associate Professor of Mathematics
University of Washington
http://wstein.org
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