Indeed sage: V.subspace([x*v]) == V.subspace([v])*x True
Sage matrices are allow indifferently on vectors from left to right. But of course, the action is not the same but there is no row vectors vs column vectors. sage: v*x (1, 1) sage: x*v (1, 0) Your example shows that when acting on subspaces it is actually the left action which is used... which is silly, I definitely agree, since the action on subspaces is on right. Vincent 2015-01-30 15:51 UTC+01:00, Peter Mueller <ypf...@googlemail.com>: > After hours of debugging some program code, I found out that right > multiplication of a row subspace of K^n by an element x from GL(n,K) does > *not* do what I expected! > > sage: V = GF(2)^2 > sage: v = V((1,0)) > sage: x = GL(2,2)(matrix([[1,1],[0,1]])) > sage: V.subspace([v*x]) == V.subspace([v])*x > False > > It seems that right multiplication by x actually multiplies by the > *transpose* of x? Is there any reason for that? That is even worse than the > > completely silly and error prone notation for permutation groups, where a > *right action* is written from the left, so g(h(x)) isn't (g*h)(x). > > -- Peter Mueller > > > -- > You received this message because you are subscribed to the Google Groups > "sage-support" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to sage-support+unsubscr...@googlegroups.com. > To post to this group, send email to sage-support@googlegroups.com. > Visit this group at http://groups.google.com/group/sage-support. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To post to this group, send email to sage-support@googlegroups.com. Visit this group at http://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/d/optout.
