> > What dimensions are you talking about? > > Not *that* big, actually. It can easily be more than 1000 rows/columns > (dense), but probably not much more than 3000. How much is the speed > up in that dimensions? > > Cheers > Simon
I never checked those dimensions since i always considered them too small to be interesting, here are some times: = matrix times vector = sage: A = random_matrix(GF(2),1000,1000) sage: v = random_matrix(GF(2),1000,1) sage: %timeit A*v 1000 loops, best of 3: 216 µs per loop sage: A = random_matrix(GF(2),3000,3000) sage: v = random_matrix(GF(2),3000,1) sage: %timeit A*v 1000 loops, best of 3: 808 µs per loop = vector times scalar = doesn't make sense, really = sum/difference of vectors = sage: v = random_matrix(GF(2),1000,1) sage: %timeit v+v 10000 loops, best of 3: 26.5 µs per loop sage: v = random_matrix(GF(2),3000,1) sage: %timeit v+v 10000 loops, best of 3: 62.8 µs per loop sage: v = random_matrix(GF(2),1,3000 sage: %timeit v+v 100000 loops, best of 3: 8.09 µs per loop sage: v = random_matrix(GF(2),1,1000) sage: %timeit v+v # looks like a lot of calling overhead 100000 loops, best of 3: 7.95 µs per loop = echelon form of a matrix = sage: A = random_matrix(GF(2),1000,1000) sage: %time A.echelonize() CPU times: user 0.01 s, sys: 0.00 s, total: 0.01 s Wall time: 0.01 s sage: A = random_matrix(GF(2),3000,3000) sage: %time A.echelonize() CPU times: user 0.05 s, sys: 0.00 s, total: 0.05 s Wall time: 0.06 s Generally, I'd advise to create matrices of with 1 row and n columns rather than the other way around to represent the vectors. In the M4RI library there is actually a function for multiplication with 'pre-transposed' vectors/matrices like this which will be faster. However, it is not exposed yet, but that is easy. ... maybe someone should write a Vectoer_dense_gf2 class :-) 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-support@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-support URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
