How to pick random entries from the columns of a matrix such that their sum is equal to a already specified number?

An example to clarify my question is that Let's assume a matrix

A=[ 0.8147 0.9134; 0.9058 0.6324; 0.1270 0.0975];

I want to select entries from each column such that their sum is always equal or approximately equal to a number say 1 for the above matrix. How can I do this?

Answer 1

[parham kianian]

I suppose you want to perform this on each column of matrix A seperately. Try this:

A=[ 0.8147    0.9134;  0.9058    0.6324; 0.1270    0.0975]; 
v = nchoosek(A(:,1),2);     %All possible selection of two number out of three for first column of A
                            %each row of matrix v shows one possible selection
x = abs(sum(v,2) - 1);      %sum arrays of each row of matrix v then substract it by 1 and take absolute value
                            %suppose desired solution is where the sum lies between 0.9 and 1.1
r = find(x == min(x));
best_selection = v(r,:);    %best selection of all possible selections of two number out of three

You can develop a for loop to perform on each column of matrix A or find a way to vectorize the process to enhance code performance if matrix A has large dimension.