[R] qr.coef

Roger Koenker roger at ysidro.econ.uiuc.edu
Wed Oct 4 18:18:23 CEST 2000


I've just encountered a very minor discrepancy between R and Splus that
seems a bit puzzling.  In R if you have a square (p by p) singular matrix, 
call it A, and you do,

	qr.coef(qr(A),diag(p))

you get an answer with rows of NA's.  Quite properly, I thought.  However,
in Splus you get the same result except that the NA's are replaced by 0's.
This seems to imply the convention 1/0 = 0.  Is there some deeper rationale
for this convention?  I realize that it might be more reasonable to have
sent this to Snews, but I've sworn off Snews recently in favor of this 
forum.


url:	http://www.econ.uiuc.edu		Roger Koenker	
email	roger at ysidro.econ.uiuc.edu		Department of Economics
vox: 	217-333-4558				University of Illinois
fax:   	217-244-6678				Champaign, IL 61820


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