st: Re: flip a matrix around

[Kit Baum <baum@bc.edu>]

As it happens the ability to 'flip a matrix around' horizontally or  
vertically is the subject of a forthcoming Stata Tip. As Danielle is  
using Stata 9.x a Mata solution should work fine for her.


----------------cut here------------
capture program drop get_dfglsResults
program get_dfglsResults, rclass

	version 9.2
	
	local optlag = r(maiclag)
	mata: st_matrix("r",flipud(st_matrix("r(results)")))
	local T = r[`optlag', 5]
	local df = r(N) - `optlag'
	return scalar p = ttail(`df', `T')
	
end

	mata:
	    matrix function flipud(matrix X)
        {
                return(rows(X)>1 ? X[rows(X)..1,.] : X)
        }
    end
----------------cut here---------------


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


On Aug 3, 2006, at 2:33 AM, Danielle wrote:


> The problem is that the results of dfgls for each lag are listed in  
> reverse order (i.e., results for lag m are listed first and results  
> for lag 1 are listed last). So, the line "local T = r[`optlag', 5]"  
> does not grab the right row. Can I flip the matrix r around so (or  
> re-sort the rows) so that the first row corresponds to the results  
> for lag 1 and the row m corresponds to results for lag m? Or is  
> there perhaps a better way to approach this?
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