On Thursday 15 May 2008, Bill Hart wrote: > Martin, > > Do you think Magma uses naive multiplication for its base case? This > can be ridicoulously fast, especially over GF2. I note for example > that Magma's base case is about 6 times faster than M4RI at 1000x1000. > Is it possible that the naive multiplication can just be optimised > with a far better constant and that the crossover with m4r is above > the crossover with Strassen-Winograd? > > I also note that the M4RI SSE2 code doesn't seem faster than the > generic C code on the Opteron, in fact it seems the other way around. > Very strange.
I observed the same behaviour but have no explanation besides stuff like this: http://www.theinquirer.net/en/inquirer/news/2003/05/02/sse2-makes-opterons-slower-than-athlon-xps How do you know what the Magma base case is, can you tell Magma somehow to print its crossover? I'll look into plugging in naive multiplication as the base case (after optimisation) to see if your idea is right, though I doubt that the crossover to M4RM is beyond the crossover to Strassen-Winograd. Martin -- name: Martin Albrecht _pgp: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x8EF0DC99 _www: http://www.informatik.uni-bremen.de/~malb _jab: [EMAIL PROTECTED] --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
