Find out the column number in which Maxima occur in a matrix in Mata in a for-loop - loops

Question

My purpose is not to find out what the maximum value is but the column number(S) in which the maximum occurs when generated different random numbers ~N to the entire column elements of the row.
A potential problem here is what if two or more elements in the same row contain the same value which is the maximum? I know it is unlikely for they content are real numbers. But I preset all elements in first row to be zero. Therefore, in the first round, all values are maximum and are subject to next conditional action.
I will want the column number(s) to do further computation in the next round of loop
Suppose all the matrix are well defined before the for-loop to save space here.
Mata:
for (k=1; k<=10; k++){
for (j=1; j<=20; i++){
A[k,j]= sum[k,j] \ count [1,j]
}
Choose max A[k,j]
For that j* for max A[k,j*] to occur
{count[1,j*]=count[1, j*+1]
y= rnormal(1,1,x,5)
C[k,j*]=y
sum[k,j*]=sum[k,j*]+c[k,j*]
}
}
Thank you so much for your help.

Answer 1

I can't follow most of this -- a lot seems to be background tangential to your question -- but if the question is to find the column index of the largest element in a row vector, here is one technique:
: y = rnormal(1,10,0,1)
: y
1 2 3 4 5
+----------------------------------------------------------------------------
1 | .3660763572 .4824003439 -.4441589685 .4314199623 -1.422563986
+----------------------------------------------------------------------------
6 7 8 9 10
----------------------------------------------------------------------------+
1 -1.226056129 1.18790502 -.4106889581 1.024620896 1.092570732 |
----------------------------------------------------------------------------+
: select((1..10), (y :== max(y)))
7
(LATER)
I haven't tried to grasp the whole of what you are trying to do, but you are making very bold assertions about a language you have only just started to learn.
Generally, select() will take a matrix as first argument.
Specifically, there is no problem in identifying the maximum in a matrix.
: y = rnormal(5,5,0,1)
: max(y)
2.001071729
: y :== max(y)
1 2 3 4 5
+---------------------+
1 | 0 0 0 0 0 |
2 | 0 0 0 0 1 |
3 | 0 0 0 0 0 |
4 | 0 0 0 0 0 |
5 | 0 0 0 0 0 |
+---------------------+
I hope that helps a bit.

Answer 2

for (k=2; k<=n; k++){
for (j=1; j<=50; j++){
Ri[k,j]= sumAi[1,j] / count[1,j]
}
Maxj= select((1..50), (Ri[k,]:==max(Ri[k,])))
count[1,Maxj]=count[1,Maxj]+1
y= rnormal(1,1,x,5)
Ai[k,Maxj]=y
sumAi[1,Maxj]=sumAi[1,Maxj]+y
Maxj=.
}