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st: Re: RE: Re: RE: Re: RE: summing up matrix elements


From   "R.E. De Hoyos" <redeho@hotmail.com>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: Re: RE: Re: RE: Re: RE: summing up matrix elements
Date   Tue, 8 Nov 2005 18:49:47 -0000

Nick,

Thanks for advice and the references. Rafa

----- Original Message ----- From: "Nick Cox" <n.j.cox@durham.ac.uk>
To: <statalist@hsphsun2.harvard.edu>
Sent: Tuesday, November 08, 2005 6:24 PM
Subject: st: RE: Re: RE: Re: RE: summing up matrix elements



OK. Jamie's solution is still presumably better
in Stata 8. When Jeroen and then I wrote
some crude matrix add-ons in 1997-2000,
-vec()- had not been implemented, I believe.

STB-56 dm79 . . . . . . . . . . . . . . . . . . Yet more new matrix commands
(help matcorr, matewmf, matvsort, svmat2 if installed) . . N. J. Cox
7/00 pp.4--8; STB Reprints Vol 10, pp.17--23
commands to produce a correlation matrix, elementwise monadic
function of another matrix, selected subsets of matrix rows
and columns, vec or vech of a matrix, elements sorted within
a vector, matrix from a vector, and commands to save matrices

STB-50 dm69 . . . . . . . . . . . . . . . . . . Further new matrix commands
(help matdelrc, matewm, matmad, matpow if installed) . . . N. J. Cox
7/99 pp.5--9; STB Reprints Vol 9, pp.29--34
collection of new matrix commands providing additional matrix
checking, management, element-wise operators, maximum absolute
difference, and power

STB-39 dm49 . . . . . . . . . . . . . . . . . . . . Some new matrix commands
(help matfunc, varfunc if installed) . . . . . . . . . . . J. Weesie
9/97 pp.17--20; STB Reprints Vol 7, pp.43--48
collection of new matrix commands; several for explicit matrices
and a few for implicit matrices (i.e., variables)

Nick
n.j.cox@durham.ac.uk


-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu
[mailto:owner-statalist@hsphsun2.harvard.edu]On Behalf Of
R.E. De Hoyos
Sent: 08 November 2005 18:15
To: statalist@hsphsun2.harvard.edu
Subject: st: Re: RE: Re: RE: summing up matrix elements


> Offhand, I can't think of any reason why anyone
> with Stata 9 would prefer that. Nor, I imagine,
> would Jeroen if he were to be asked.

I have access to Stata 9 only when I am in the University, in
my laptop I
have version 8.

Rafa

----- Original Message ----- From: "Nick Cox" <n.j.cox@durham.ac.uk>
To: <statalist@hsphsun2.harvard.edu>
Sent: Tuesday, November 08, 2005 5:59 PM
Subject: st: RE: Re: RE: summing up matrix elements


> You may be thinking of Jeroen Weesie's -matsum-.
> Offhand, I can't think of any reason why anyone
> with Stata 9 would prefer that. Nor, I imagine,
> would Jeroen if he were to be asked.
>
> STB-39 dm49 . . . . . . . . . . . . . . . . . . . . Some
new matrix
> commands
> (help matfunc, varfunc if installed) . . . . . . .
. . . . J.
> Weesie
> 9/97 pp.17--20; STB Reprints Vol 7, pp.43--48
> collection of new matrix commands; several for
explicit matrices
> and a few for implicit matrices (i.e., variables)
>
> Nick
> n.j.cox@durham.ac.uk
>
> R.E. De Hoyos
>
>> Both your solutions work fine, thanks a lot.
>> I though there was a non-mata matrix function similar to
>> mata's -sum(C)-
>
> Nick Cox
>
> . mata : sum_r = (sum(C) - trace(C)) / 2
>
> 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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