On 10/7/07, Ralph G Selfridge <[EMAIL PROTECTED]> wrote: > We should be careful of using 'historic' reasons. Have you ever tried to > convince a mathematican that matrix multiplication (+/ .*) can be on other > than rank 2? And some time ago I had an argument that there are no such > things as a row vector or a column vector, a vector is a vector is a > vector. Row and column vectors are just ways of talking about a matrix with > a 1 in its shape.
I agree with your last sentence -- row vectors and column vectors are both ways of expressing vectors using matrices. But that doesn't mean they don't exist. Given a vector v ,:v produces the corresponding row vector and ,.v produces the corresponding column vector. I think it's often simpler to just work with vectors, but a mathematician who wants to apply a proof about matrices to a vector might find row or column vectors more suitable. -- Raul ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
