On Mon, Feb 6, 2012 at 6:49 AM, John Cremona <john.crem...@gmail.com> wrote: > I was trying to find eigenspaces of a 26x26 matrix over Q(zeta_11) > (for a modular forms application) and ran into:
Can you make your matrix available, e.g., as an sobj on sage.math (or somewhere) that I can download. It's possible that the real problem is a bug in the echelon routine, not the size of the modulus. If the multimodular echelon fails to stabilize -- due to a bug -- then the consequence is that eventually the primes would run out. However, this is highly unlikely to happen in practice unless the entries of the answer are truly gigantic. -- William > > RuntimeError: we ran out of primes in multimodular charpoly algorithm > > which on investigation led me to the following lines in > sage/ext/multi_modular.pyx: > > # We use both integer and double operations, hence the min. > # MAX_MODULUS = min(int(sqrt(int(MOD_INT_OVERFLOW))-1), int(2)**int(20)) > > # Hard coded because currently matrix_modn_dense is implemented using C ints > # which are always 32-bit. Once this gets fixed, i.e., there is a better > # matrix_modn class, then this can change. > MAX_MODULUS = 46341 > > so I am just wondering if anyone out there has this on their to-do > list. Meanwhile using algorithm='pari' will have to do, though it is > slow.... > > This is a small trial run. We'll be doing a 50x50 over Q(zeta_13) for > real.... > > John > > -- > 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 > URL: http://www.sagemath.org -- William Stein Professor of Mathematics University of Washington http://wstein.org -- 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 URL: http://www.sagemath.org
