Robert Miller wrote: > Hello all, > > For those of you not in Seattle today / not at Chris's talk at the > Sage seminar, here is a copy of his slides. >
Thanks! (and thanks, Chris, if you are listening too). Some comments/questions: 1. What did Chris use to draw the graphs on page 48? The drop-shadow looks very nice, for example. 2. determinants (p. 56): For the general case, we use LU decomposition now, instead of expansion by minors, so I don't think it is exponential time these days. Integer and rational determinants are computed using a different algorithm, I believe. sage: a=random_matrix(SR, 25) sage: type(a) <type 'sage.matrix.matrix_symbolic_dense.Matrix_symbolic_dense'> sage: len(a.nonzero_positions()) 509 sage: %time a.determinant() CPU times: user 0.22 s, sys: 0.00 s, total: 0.22 s Wall time: 0.23 s -4932640057384336 For integer matrices: sage: b=a.change_ring(ZZ) sage: len(b.nonzero_positions()) 509 sage: %time b.determinant() CPU times: user 0.00 s, sys: 0.00 s, total: 0.00 s Wall time: 0.00 s -4932640057384336 sage: %timeit b.determinant() 1000000 loops, best of 3: 472 ns per loop Thanks again for posting these slides. It looks like it was a great talk! Jason -- Jason Grout --~--~---------~--~----~------------~-------~--~----~ To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
