Op donderdag 8 november 2012 10:36:51 UTC+1 schreef John Cremona het volgende: > > Either I am doing something wrong or a simple operation which should > be fast is in fact very slow, but I do not know why. > > If V,W are vector spaces over QQ, subspaces of the same ambient > space, then V.sum(W) should return their sum, with an echelon basis > obtained from the bases of V and W. But this takes a stupidly long > time. For example: > > sage: Q100=QQ^100 > sage: V=Q100.subspace([Q100.random_element()]) > sage: W=Q100.subspace([Q100.random_element()]) > > # so V,W are both 1-dimensional > > sage: V.sum(W) > sage: time V.sum(W) > > # takes forever (on 5.3) -- why? > > It's even slow for
sage: Q100 = QQ^1 To find out where things are slow, you can use %prun, which gives a list of functions and the time spent in each. I haven't had time to look into it yet, but perhaps you'll be able to find out what's going that way. You could also apply patch #5814 and use %prun from the notebook. Best, Timo -- You received this message because you are subscribed to the Google Groups "sage-devel" group. 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. Visit this group at http://groups.google.com/group/sage-devel?hl=en.
