Using an if condition in a for loop

[Chinmay Sharma]

I am currently working with Mata. The dataset in Mata currently contains vectors A and B of dimension N*1 each. In summary, what I am trying to do is to :

1. create another vector of random terms of the same dimension drawn from a normal distribution
2. Sum element wise this vector to vectors A and B
3. Evaluate if the sum is greater than 1 or less than 0
4. If 3) is true for a particular element , redraw the random term till the condition holds
5. Do this for all terms until each element of this vector which is the sum of A, B and the error term is either less than 1 or greater than 0. The following is the code I have written till now

putmata A B \\this inputs these vectors in mata
Sum=J(rows(A), 1,0) \\\Creates a vector with each element 0- to loop over.
for (i=1;i<=rows(A);i++) {
Random[i,1] = rnormal(1,1,0,1)
Sum[i,1]=A[i,1]+B[i,1]+Random[i,1]
while (Sum[i,1]>1) {
Random[i,1]= rnormal(1,1,0,1))
}

}
end

!
This does not work- I still get values greater than 1 and less than 0.
I think I see the problem, but not the syntax. There should be another condition here to keep on doing the drawing of the term till the statement is true. I am not sure if the while statement enforces this. Any help is greatly appreciated!

[Chinmay Sharma]

Just as an addition, the dataset I have is as follows:

* Example generated by -dataex-. To install: ssc install dataex
clear
input float(A B)
.2  .5
 0  .6
.3 .21
.5  .4
.6  .5
.1  .1
.2  .5
end

[Chinmay Sharma]

Thanks to a suggestion on a different forum, I have been able to produce the desired result. The correct code is as follows:


putmata A B \\this inputs these vectors in mata Sum=J(rows(A), 1,0) \\\Creates a vector with each element 0- to loop over. for (i=1;i<=rows(A);i++) { Random[i,1] = rnormal(1,1,0,1) Sum[i,1]=A[i,1]+B[i,1]+Random[i,1] while (Sum[i,1]>1) { Random[i,1]= rnormal(1,1,0,1) Sum[i,1]=A[i,1]+B[i,1]+Random[i,1] } } end

[Nick Cox]

Indeed; you cross-posted at http://stackoverflow.com/questions/3...r-loop-on-mata

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