Dear Hans and sage-devel readers, As I wrote on sage-devel a bit earlier, I had some polynomials that were causing singular gcd to slow down dramatically. I had thought this was inconsistent, but upon more investigation it seems very consistent (on two different computers).
Here's some singular code to illustrate the problem. The first one computes the gcd slowly, but not too bad (several seconds). http://sage.math.washington.edu/home/jbmohler/gcd_fast.singular This one takes a long time on my computer (at least a couple of minutes). http://sage.math.washington.edu/home/jbmohler/gcd_slow.singular Those time indications are on a P4 2.4 ghz. Memory usage of the Singular executable is listed in 'top' at 12 MB (which seems perfectly reasonable to me). Note also that mathematica (on sage.math) can write the ratio of these polynomials in reduced form with-in a second (I'm supposing it computes a gcd on the way to doing this). I computed the semi-random polynomials from this python script: http://sage.math.washington.edu/home/jbmohler/singular_vs_mathematica.py Basically, they are products of binomials of the form (1-{x0}^{e0}*...*{xn}^{en}) where the {ei} are chosen randomly from {0,1}. I multiply about 8-12 of these together to get polynomials of approximately 2^8 to 2^12 monomials. There is a huge speed difference between n=4 and n=5 (5 variables vs. 6 variables). It also seems to make a difference if I select my {ei} from a larger set (say {0,1,...,10}). This seems to be significantly faster (I'm guessing it's because the gcd is of lower degree). I've now reproduced this with the singular that is built from sage and also with a singular build from the singular website (3.0.3-ix86-Linux). Thanks Joel --~--~---------~--~----~------------~-------~--~----~ 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-devel URLs: http://sage.scipy.org/sage/ and http://modular.math.washington.edu/sage/ -~----------~----~----~----~------~----~------~--~---
