Hi, One can always work around a problem, but it would be better to discuss the best approach and put this in place.
A related problem I had recently was in finding a random element of GL_n(ZZ/26ZZ) where n was 20-30. It was failing to terminate in the determinant computation. My guess is that a determinant over ZZ was being computed and reduced but that the resulting determinant was too big. I didn't verify this, but invite someone to check. Instead I worked around this by computing the determinants mod 2 and mod 13 and using CRT (if the determinants were both units). The time was then almost trivial. Suppose I replace this problem over ZZ/25ZZ or ZZ/256ZZ. I would still hope that the problem would NOT be lifted to ZZ for computation, since this would certainly not terminate in reasonable time for a dense matrix. Taking the approach of lifting to ZZ for charpolys of matrices of non-trivial size will undoubtably lead to exactly the same coefficient explosion which is the presumed source of the problem with determinants over ZZ/26ZZ. --David --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send 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 -~----------~----~----~----~------~----~------~--~---
