How to get each pair of of row of a matrix to pass into a function?

Hello Friends,

I have a matrix A of size N x M. I want to get all possible pair of rows, pass them into a function, and get the N x N matrix as output. To be more precise, here is an example of what I want to do:

Example:
Let, A = [1 2; 3 4; 5 6];
Possible row pairs are: {row1, row1}, {row1, row2}, {row1, row3}, {row2, row1}, {row2, row2}, {row2, row3}, {row3, row1}, {row3, row2}, {row3, row3}.

So output will be a 3 x 3 matrix after employing the following steps:

Step-1 For each pair(i,j) or row above
Step-2 function1 = sum(row_i);  and function-2 = product(row_j);
Step-3 function3 = sqrt(function1, function2);
Step-4 go to Step-1 and repeat for each pair.

Output Matrix = [f3 f3 f3; f3 f3 f3; f3 f3 f3];

I will appreciate any advice.

Answer 1

[Star Strider]

This seems to approximate what your Question specifies:

A = [1 2; 3 4; 5 6];
nk = [];
for k1 = 1:size(A,1)
    for k2 = 1:size(A,1)
        nk = [nk; k1 k2];
    end
end
for k1 = 1:size(nk,1)
    f1(k1) = sum(A(nk(k1,1),:));
    f2(k1) = prod(A(nk(k1,2),:));
    f3(k1) = f1(k1).^2 + f2(k1).^2;     % Best Guess At: ‘square(function1, function2)’
end
OutputMatrix = reshape(f3, [], 3);

The ‘nk’ variable begins as the combinations of the row numbers taken two at a time. It then loops through, calculating the various function values. You will probeably want to re-define ‘f3’, since I am not clear on your description of it.

EDIT — Added ‘OutputMatrix’, minor recalculation of ‘nk’.

[Star Strider]

My pleasure.

I forgot that you want the rows duplicated, so I added a repmat call to ‘nk’ to accommodate them. The edited code now includes all combinations of them.

Answer 2

[the cyclist]

I didn't understand Step 3, but this code will do the parts up to there:

A = [1 2; 3 4; 5 6];

[M,N] = size(A);

for m1 = 1:M
    row1 = A(m1,:);
    s = sum(row1);
    for m2 = 1:M
        row2 = A(m2,:);
        p = prod(row2);
    end
end