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


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: Re: RE: Re: RE: summing up matrix elements
Date   Tue, 8 Nov 2005 18:24:09 -0000

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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