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st: RE: summing up matrix elements


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: summing up matrix elements
Date   Tue, 8 Nov 2005 15:28:22 -0000

. mata : sum_r = (sum(C) - trace(C)) / 2
 
Nick 
n.j.cox@durham.ac.uk 
 
R.E. De Hoyos
  
> > Is there a way to to get a scalar containing the sum of the 
> > off-diagonal 
> > elements of a pre-defined matrix?
> > 
> > For instance, define matrix C  as a correlation matrix. I 
> > want to know what 
> > is the sum of correlations between the various elements in C. 
> > Therefore I 
> > need the sum of all elements in C minus the sum of the 
> > diagonal elements 
> > (-trace(C)-) and finally divide it by 2 (I am assuming matric C is 
> > symetric).
 
 

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