st: re: how to form a vector for each line

[Christopher Baum <baum@bc.edu>]

<>
Nick said

Some readers may find Martin's opening sentence a little puzzling,  
however. In Stata, as compared with Mata, there is no difficulty in  
setting up row or column vectors, which are just matrices with one row  
or column. In this sense, Stata has had the idea of vector for several  
versions now.

To be pedantic, Stata (as opposed to Mata) does not and never has had  
vectors. Vectors are ordered arrays with a *single* subscript. There  
is no way to create such an object in Stata. You can have matrices  
with one row or one column (or both) that look like vectors, but to  
use them you must include both a row subscript and a column subscript  
in the notation. In that annoying way, Stata's old matrix language  
does not allow vectors at all. Mata has the concept of a vector, and  
allows you to reference an element as nj[42] rather than nj[42,1] or  
nj[1,42]. IMHO this is a good reason to avoid the old matrix language  
when you can, as it unnecessarily complicates working with 'real'  
vectors such as e(b).

Kit Baum   |   Boston College Economics and DIW Berlin   |   http://ideas.repec.org/e/pba1.html
An Introduction to Stata Programming   |   http://www.stata-press.com/books/isp.html
An Introduction to Modern Econometrics Using Stata   |   http://www.stata-press.com/books/imeus.html

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