On Sep 7, 2008, at 6:56 AM, Jason Merrill wrote: > > On Sep 7, 6:30 am, "John Cremona" <[EMAIL PROTECTED]> wrote: >> It should be lightly easier than it is to convert a vector of >> length n >> to either an nx1 matrix or a 1xn matrix: >> >> sage: v = vector(srange(5)) >> sage: v >> (0, 1, 2, 3, 4) >> sage: matrix(QQ,1,5,[v]) >> [0 1 2 3 4] >> sage: matrix(QQ,5,1,list(v)) >> >> [0] >> [1] >> [2] >> [3] >> [4] >> >> I got neither of those right the first time! I know that v*v is >> short >> for the dot product, which is also (row v)*(col v), but sometimes one >> wants (col v)*(row v) as a rank 1 nxn matrix: >> >> sage: matrix(QQ,5,1,list(v)) * matrix(QQ,1,5,[v]) >> >> [ 0 0 0 0 0] >> [ 0 1 2 3 4] >> [ 0 2 4 6 8] >> [ 0 3 6 9 12] >> [ 0 4 8 12 16] >> >> I suggest that vector methods row_matrix() and col_matrix() would >> be useful. > > It might be nice to have row_matrix() and col_matrix(), as you > suggest, but you can do the conversions right now like this: > > sage: matrix(v) > [0 1 2 3 4] > > sage: transpose(v) > > [0] > [1] > [2] > [3] > [4] > > sage: parent(transpose(v)) > Full MatrixSpace of 5 by 1 dense matrices over Integer Ring
I'm not sure I like this... I think it makes more sense to do transpose(matrix(v)). > > # This is a bug, I guess > sage: matrix(transpose(v)) > Traceback (most recent call last) > ... > TypeError: _matrix_() takes exactly one argument (0 given) Yep, I'd say that's a bug. - Robert --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
