|Bill Allombert on Wed, 4 Dec 2002 16:55:34 +0100|
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|Re: Comparaison between PARI MPQS, PPMPQS and PPSIGS|
On Tue, Dec 03, 2002 at 04:34:56PM -0500, Igor Schein wrote: > On Wed, Nov 27, 2002 at 05:26:39PM +0100, Bill Allombert wrote: > > Hello developers, > > > > I have factored > > 117433370311644622074182931512170893877890957626285922622753078073774028918529 > > (78 digits) > > > > on a 1GHz PIV > > with PARI (2.2.5), and then I try PPMPQS (2.8) and PPSIGS (1.1) from > > http://www.asahi-net.or.jp/~KC2H-MSM/cn/ > > > > here the running time: > > PARI : 3h 9 min > > PPMPQS : 1h 58 min > > PPSIGS : 1h 46 min > > > > Karim's FAQ states > > > > > PARI's MPQS is about as fast as PPMPQS-2.7 in the 60 digits range, and much > > > slower afterwards, e.g already 3 times slower for 70 digits. We have not > > > tested mpqs4linux. > > Well, here's a problem with PARI's MPQS on Linux which I noticed some > time ago. If you run N consecutive factorizations with PPxxxx on the > same number, the timing results will be consistent. Not so the case > for PARI. Here's the timings for several consecutive MPQS > factorizations of C78 above on an otherwise empty machine: For the record, my timings were done two time each and I got consistent results. Maybe it is a difference in disk usages, maybe PPMPQS as its own internal buffering. Also they do not store temporary files in the same directory. This can make a difference. Also you may want to delete the temporary files created between each run. > The speed is constant within each session, it's just that some > sessions are faster, some sessions are slower for no apparent reason. > > Based on above, it's really hard to compare speed for this size > integer on Linux. However, I was able to obtain more consistent > results for C60=nextprime(10^60)*precprime(10^60) - PPSIGS is almost > twice faster than PARI on a 512MB full speed L2 cache Linux machine. I suppose you mean nextprime(10^30)*precprime(10^30), else you must have a Cray. Cheers, Bill.