Pick 5 Unique Random Numbers

I am still trying to learn MATLAB. It would be helpful if I get some knowledge from this problem. So here is a simpler version of my problem. ( I wish to learn from this and use it in my actual problem)

I have Matrix defined by:

A=zeros(10,10);
for i=1:10
    for j=1:10
            A(j,i)=i*100+j;
    end
end

I wish to pick 5 Random but Unique terms in the Matrix A, do some operation (for example: addition of all 5 terms) and from the result, I will make a column Matrix B by populating each row with one result from addition of 5 random unique terms in A, till I run out of all terms in A.

I know how to perform operations on the 5 terms from A and to populate B but I don't know how to get the 5 Random Unique terms from A. Can someone please help me with this.

Answer 1

[James Tursa]

A = your matrix
n = number of elements of A to pick at a time (must be exactly divisible in numel(A))
x = reshape(randperm(numel(A)),n,[]); % Create some random non-repeating indexing
for k=1:size(x,2)
    % The elements of A to use for this iteration are A(x(:,k))
end