R help - Jun 2006 - princomp and prcomp confusion

When I look through archives at
https://stat.ethz.ch/pipermail/r-help/2003-October/040525.html

I see this:

Liaw, Andy wrote:
>In the `Detail' section of ?princomp:
>
>princomp only handles so-called Q-mode PCA, that is feature extraction of
>variables. If a data matrix is supplied (possibly via a formula) it is
>required that there are at least as many units as variables. For R-mode PCA
>use prcomp. 
>
It doesn't appear that anyone disputed the accuracy of it.


My current installation (version.string Version 2.3.1 (2006-06-01))
says in the detail of princomp


     'princomp' only handles so-called R-mode PCA, that is feature
     extraction of variables.  If a data matrix is supplied (possibly
     via a formula) it is required that there are at least as many
     units as variables.  For Q-mode PCA use 'prcomp'.

I've not been following principal components and have only recently
had a use for that methodology.  Am I to assume that the later version
is the correct one?  I thought I'd worked out what the distinction
between R-mode and Q-mode was, but now I'm as confused as ever.

best

-- 
~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.   
   ___    Patrick Connolly   
 {~._.~}          		 Great minds discuss ideas    
 _( Y )_  	  	        Middle minds discuss events 
(:_~*~_:) 	       		 Small minds discuss people  
 (_)-(_)  	                           ..... Anon
	  
~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.

From: Patrick Connolly
> 
> When I look through archives at
> https://stat.ethz.ch/pipermail/r-help/2003-October/040525.html
> 
> I see this:
> 
> Liaw, Andy wrote:
> 
> >In the `Detail' section of ?princomp:
> >
> >princomp only handles so-called Q-mode PCA, that is feature 
> extraction 
> >of variables. If a data matrix is supplied (possibly via a 
> formula) it 
> >is required that there are at least as many units as variables. For 
> >R-mode PCA use prcomp.
> >
> 
> It doesn't appear that anyone disputed the accuracy of it.
> 
> 
> My current installation (version.string Version 2.3.1 
> (2006-06-01)) says in the detail of princomp
> 
> 
>      'princomp' only handles so-called R-mode PCA, that is feature
>      extraction of variables.  If a data matrix is supplied (possibly
>      via a formula) it is required that there are at least as many
>      units as variables.  For Q-mode PCA use 'prcomp'.
> 
> I've not been following principal components and have only 
> recently had a use for that methodology.  Am I to assume that 
> the later version is the correct one?  I thought I'd worked 
> out what the distinction between R-mode and Q-mode was, but 
> now I'm as confused as ever.
>From what I can gather by googling around about R-mode and Q-mode PCA, 
the current description should be the correct one.  

Andy

> best
> 
> -- 
> ~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.
> ~.~.~.~.~.   
>    ___    Patrick Connolly   
>  {~._.~}          		 Great minds discuss ideas    
>  _( Y )_  	  	        Middle minds discuss events 
> (:_~*~_:) 	       		 Small minds discuss people  
>  (_)-(_)  	                           ..... Anon
> 	  
> ~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.
> ~.~.~.~.~.
> 
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