On Thu, Mar 19, 2009 at 9:33 PM, Rob Beezer <[email protected]> wrote: > > Chris, > > Some flakiness with Google Groups. Here's the rest of what I wanted > to say. > > Sage is *very* fast over ZZ, and I know you said that was irrelevant. > Use the command in the previous message to scale out the fractions, do > your computation, and then move the scalar back in to the result. Not > sure what you are up to exactly, but with determinants and > polynomials, perhaps the scaling has a predictable effect. I like the > looks of Mike's suggestion very much, and if this helps you get there, > then I think thousands of 30x30's are achievable. >
Mike's "multimodular method" is probably a pretty good first nontrivial approach to this problem. Chris -- you might want to talk with Arne Storjohann since he's probably the world expert on algorithms for computing determinants of matrices with entries in QQ[t], and he's in the same department as you. He's also responsible for IML, which is the library at the heart of Sage's current code for computing det's over QQ and ZZ. Asymptotically -- for matrices with large entries -- Sage is by far the world's fastest program for computing determinants (e.g, handily beating Magma). Rob -- Sage computes det's over QQ currently internally by rescaling to ZZ and computing the det there. -- William --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to [email protected] 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 -~----------~----~----~----~------~----~------~--~---
