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RE: st: RE: Adding Matrices generated from a loop


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   RE: st: RE: Adding Matrices generated from a loop
Date   Fri, 24 Aug 2007 14:25:00 +0100

Well, initialise outside the loop, and add each replaced 
t_i to the sum so far each time round the loop. Naturally, 
all the matrices must be conformable. 

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

Nadeem Shafique
 
> Sorry for not providing complete information, I am trying it using
> Mata. Following is the code i am trying to execute.
> 
> **************************************************************
> ******************************
>   for (i=1; i<=rows(info); i++)
> 					{
>                                                                  v_i =
> panelsubmatrix(v, i, info)
> 				m_i = panelsubmatrix(m,i,info)
> 				n_i = panelsubmatrix(s,i,info)
> 				n = mean(n_i)
> 				t_i=v_i*m_i*n
> 
>                     }
> 
> ****************** I want to sum all these t_i in one matrix say "t"

 
> On 8/24/07, Nick Cox <n.j.cox@durham.ac.uk> wrote:
> > There may be subtleties here I am missing, but
> > I would initialise
> >
> >        sum <- first_matrix
> >
> > and then loop over the other matrices
> >
> >        sum <- sum + next_matrix
> >
> > This is pseudocode.
> >
> > Otherwise I can't tell what's troubling you about
> > this. As the details will depend on whether
> > you are using Stata or Mata, your naming structure,
> > what else you are doing with these matrices,
> > whether the number is predictable in advance, etc.,
> > none of which is indicated, I'll leave it there.

> > Nadeem Shafique
> >
> > > I want to add several matrices (say K) of the same order, 
> suppose the
> > > matrices to be added are comming from a loop, how can i 
> calculate the
> > > following
> > >
> > >                 K
> > >                 Sum    X_i
> > >                 i=1
> > > where X_i is the ith Matix

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