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Re: st: basic mata structure question


From   Matthew Weinberg <mweinber@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: basic mata structure question
Date   Mon, 17 Sep 2007 17:09:04 -0400

Got it.  Thanks Ben.--Matt

Ben Jann wrote:
Matthew, what you get back is the address of the created struct. In
oder to use the returned structure, you have to declare it beforehand
(note that you cannot use structures in interactive mode). You could
code something like the following:

function whatever()
{
struct mups scalar ms

...
ms = markups(s,p,b)
... ms.margins ...
... ms.marks ...
...
}

ben

On 9/17/07, Matthew Weinberg <mweinber@terry.uga.edu> wrote:

I'm trying to use structures for the first time and am having a little
trouble.
I want the function markups to take three arguments (s,p,b) and return
three arguments (margins, marks, and costs). I'm getting back one

My code is:

mata
struct mups{ /*define the structure*/
real matrix margins
real matrix marks
real matrix costs
}

struct mups function markups(s,p,b) /*define the function*/
{
struct mups scalar ms /*declare structure variable*/
n=rows(s)
S=J(n,n,0)
for(i=1;i<=n;i++){
for(j=1;j<=n;j++){
S[i,j]=-b*s[i]*s[j]
}
}
for(i=1;i<=n;i++){
S[i,i]=-b*s[i]*s[i]+b*s[i]
}
Omega=I(n)*S
ms.margins=invsym(Omega)*s
ms.costs=p-ms.margins
ms.marks=(p-ms.costs):/p
return(ms)
}
end

When I evaluate my function, I get back what something like 0x27c65c
instead of the three vectors margins, costs, and marks. I'd really
appreciate it if somebody could tell me what I'm doing wrong. Thanks, Matt

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