Matrix addition in a loop in a random column

I have written a code, in which a block of 1x1 gets added to a Matrix of zeros M=zeros(10,10); and shifts the block from round to round one position down. My Problem is, that the Block is fixed in Column 1 but I want it to be in a Random position in Line 1. How can I implement this?

The other Problem is, that I want this block to be bigger than just 1x1. I want it to be 2x2 big. So I guess the code for this is: M(1:2,1:2)=1; but when I just change every Vektor Like M(1)=M(1)+1; to M(1:2,1:2)=M(1:2,1:2)+1 it doesnt work.. so my question is, how can I change these 1x1 blocks to 2x2 blocks, randomly placed in Line 1, so that everything still works?

Y=10;
X=10;
Matrix=zeros(Y,X);

for n=0:6
    Matrix(1)=Matrix(1)+1;
        
     for k=2:Y
         Test = Matrix(k)+1;
         
          if Test == 1    
           Matrix(k-1) = 0;
           Matrix(k) = 1;
           disp(Matrix)
          end 
     end 
end

Thank you!

Answer 1

[dpb]

Must reference the same size section of array on LHS of an assignment as the RHS unless assign the entire LHS variable to RHS.

So if M is the large array and m is the smaller, then

szm=2;          % define the size of m
m=ones(szm);    % define square of 1s of szm x szm
...
M(i:i+szm-1,j:j+szm-1)=m;   % assign m to M at 1,j location for upper rh corner of m
...

Do the same thing for the array of zeros to write at the previous location before the new location.

As for a random colum, just use

szM=size(M,1);          % size of the matrix M
j=randi([1 szM]);       % pick random integer between 1 and szM (size of M)

to pick the j column randomly for each iteration.