st: Mata query

[Kit Baum <baum@bc.edu>]

sacrificial lamb

Ade wonders what

select(0,1) versus select(0,0) does.

Try

a = select(0,1)
b = select(0,0)
mata describe

and you will see that the first returns a scalar, whilst the second  
returns a matrix b[0,0]. I believe that is what is known as a void  
matrix. Examining the help for void matrices might be useful. Also  
compare to standard Stata function nullmat().

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


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