On Fri, 19 Feb 2010 05:51:46 -0800 William Stein <[email protected]> wrote:
> I am sending this to sage-support.... > > On Thursday, February 18, 2010, Joerg Arndt <[email protected]> wrote: > > The following doesn't finish in reasonable time: > > ------------------------ > > var('E1, E2, E4, E5, E10, E20'); > > var( 'q' ); > > t=(E20^16*E5^8*q^4*E2^24 + (-E20^16*E5^8*q^4*E4^8*E1^16 + (-E10^24 > > + E20^8*E5^16)*E4^16*E1^8)) factor(t) > > ------------------------ > > > > Session: > > % time sage < bug.sage > > ---------------------------------------------------------------------- > > | Sage Version 4.3.2, Release Date: 2010-02-06 > > | | Type notebook() for the GUI, and license() for information. > > | > > ---------------------------------------------------------------------- > > ## (hitting ctrl-Z here as ctrl-C doesn't have any effect) sage: > > Exiting SAGE (CPU time 1m19.28s, Wall time 1m21.25s). % kill %1 > > /opt/sage/sage < bug.sage 81.03s user 0.84s system 94% cpu 1:26.67 > > total ## (note: job doesn't finish within 10 minutes either) > > > > > > IIRC versions 3.* of sage did not have this problem. > > > > Note: use ginac's routine, it should be quite fast. We use Singular to factor symbolic expressions which can be represented as multivariate polynomials over QQ. In this case Singular's factorization routine is taking forever to finish, and CTRL-C doesn't seem to kill it. We don't use _sig_on/_sig_off if there are <5 monomials for some reason. Earlier versions of Sage use maxima to factor symbolic expressions. I called maxima directly using sage: t.._maxima_().factor() and that is still running for >9 minutes now. AFAIK, the Singular group is working to improve their multivariate factorization routines. Maybe this will be one of the topics we work on at Sage days 26 in Kaiserslautern. Cheers, Burcin -- 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 URL: http://www.sagemath.org
