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st: How do I suppress output in mata?


From   Kramer <kramersdomain@yahoo.com>
To   statalist@hsphsun2.harvard.edu
Subject   st: How do I suppress output in mata?
Date   Sun, 15 Nov 2009 01:11:10 -0800 (PST)

Hello - 

I'm working in Stata version 10 on a Mac.

I've just written my first function in mata and I need some help.  My function takes a column vector of length r, and creates a r x r matrix with elements that equal 1 if two elements of the column vector are the same, and zero otherwise.  The function works well, except for the fact that it returns the r x r matrix to the screen.  Since the vectors that I need to input are 5000-6000 rows long, this is a problem.  I've tried typing "quietly" before I execute the function in mata, and that returns the error: 

invalid expression
r(3000);

I've tried adding the word "quietly" before the return line in my function, i.e.:

quietly return(WDY0)

but then I got this error message:

'return' found where almost anything else expected

I've looked through the "programing" and "mata" documentation, along with  Stata help and the statalist archives (and Google) and can't figure out a solution to this problem.  If anyone has an answer, it would be much appreciated.  I've included the text of my program below.

Thank you for your consideration,

Kramer

*this is a do-file to create the function "district"
*   "district" takes the district number observation from each school and 
*   creates a matrix whose elements are one if school i != school j AND if
*   school i and school j are in the same district

*INPUTS: T = column vector of district numbers from a given year

* OUTPUT: WDY0 = matrix whose elements are one if school i != school j AND if
*                school i and school j are in the same district

mata:

real matrix district(real colvector T)
{
        real scalar r
        real matrix A
        real matrix B
        real scalar i
        real matrix WDY0

        r = rows(T)
        
        A = J(r,r,0)
        for(i=1; i<=r; i++){
            A[i,.]=T'
            }

        B = J(r,r,0)
        for(i=1; i<=r; i++){
            B[.,i]=T
            }        
            
        WDY0 = A - B
        
        for(i=1; i<=r; i++){
            for(j=1; j<=r; j++){
                if((WDY0[i,j]==0) & (i!=j))
                    WDY0[i,j] = 1
                else WDY0[i,j]=0
                }
            }
            
        return(WDY0)
}

mata mosave district(), dir(/Users/Kramer/Desktop/Thesis/) replace

end



      

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