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st: Re: RE: summing up matrix elements


From   "R.E. De Hoyos" <redeho@hotmail.com>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: Re: RE: summing up matrix elements
Date   Tue, 8 Nov 2005 16:23:14 -0000

Dear Jamie and Nick,

Both your solutions work fine, thanks a lot. I though there was a non-mata matrix function similar to mata's -sum(C)-

Best regards,
Rafa


----- Original Message ----- From: "Nick Cox" <n.j.cox@durham.ac.uk>
To: <statalist@hsphsun2.harvard.edu>
Sent: Tuesday, November 08, 2005 3:28 PM
Subject: st: RE: summing up matrix elements



. 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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