A matrix is indexed like this: A(row,column). So to traverse a single column you leave the second value the same while changing the first value. If you want to find all the values in a column larger than a threshold you can do
A(:,col)>T1;
You can easily count them by using sum
sum(A(:,col)>T1);
You can also replace those values easily like this
A(A(:,col)>T1,col) = 10;
In that we are saying to set the values of A in the desired column that are larger than T1 are to be set to ten.
I am not what it is you are saying but here is a way to do what I think you are describing and if it is not quite right, hopefully I have given you what you need to figure out how to do it.
for n = 1:size(A,col)
if A(n,col) > T1 & sum(A(1:n-1,col)>T1)<T2
A(n,col) = 10;
end
end
