Kronocker product of iteration sequence

I have this code:

A=[1 0 0;1 1 0;0 1 0]
I=[1 0;0 1]
F2=[2 1;1 2]
for i=1:3
   B=0;
  for j=1:3
       B=B+A(i,j);
  end
        if B==1; 
            eval(sprintf('R%d=I',i))
        else B==2;     
                eval(sprintf('R%d=F2',i))

          end
    end

%% At the end I want to multiply all R1,R2,R3 answers like this: A=kron(R1,R2), B=kron(A,R3)

urgently need answer...thankssss

Answer 1

[Voss]

A=[1 0 0;1 1 0;0 1 0];
I=[1 0;0 1];
F2=[2 1;1 2];

Instead of using numbered variables R1, R2, R3, use a cell array:

[N1,N2] = size(A);
R = cell(1,N1); % 1xN1 cell array
for ii = 1:N1
    B=0;
    for jj=1:N2
        B=B+A(ii,jj);
    end
    if B==1
        R{ii} = I;
    else
        R{ii} = F2;
    end
end
R{:}

ans = 2×2

1 0 0 1

ans = 2×2

2 1 1 2

ans = 2×2

1 0 0 1

And you can avoid the inner loop by using the sum function:

B = sum(A,2);
N = size(A,1);
R = cell(1,N);
for ii = 1:N
    if B(ii) == 1
        R{ii} = I;
    else
        R{ii} = F2;
    end
end
R{:} 

ans = 2×2

1 0 0 1

ans = 2×2

2 1 1 2

ans = 2×2

1 0 0 1

And you can avoid the outer loop by using logical indexing:

R = cell(1,size(A,1));
idx = sum(A,2) == 1;
R(idx) = {I};
R(~idx) = {F2};
R{:}

ans = 2×2

1 0 0 1

ans = 2×2

2 1 1 2

ans = 2×2

1 0 0 1

"At the end I want to multiply all R1,R2,R3 answers like this: A=kron(R1,R2), B=kron(A,R3)"

No problem; you can do that:

A=kron(R{1},R{2}); B=kron(A,R{3})

B = 8×8

2 0 1 0 0 0 0 0 0 2 0 1 0 0 0 0 1 0 2 0 0 0 0 0 0 1 0 2 0 0 0 0 0 0 0 0 2 0 1 0 0 0 0 0 0 2 0 1 0 0 0 0 1 0 2 0 0 0 0 0 0 1 0 2

A more general way:

B = R{1};
for ii = 2:numel(R)
    B = kron(B,R{ii});
end
B

B = 8×8

2 0 1 0 0 0 0 0 0 2 0 1 0 0 0 0 1 0 2 0 0 0 0 0 0 1 0 2 0 0 0 0 0 0 0 0 2 0 1 0 0 0 0 0 0 2 0 1 0 0 0 0 1 0 2 0 0 0 0 0 0 1 0 2

[Matt J]

A more general way:

You can do this even more simply by downloading,

https://www.mathworks.com/matlabcentral/fileexchange/25969-efficient-object-oriented-kronecker-product-manipulation

B=full(KronProd(flip(R)))