The code keep giving the error of 'Empty sym: 0-by-2' .

The %error line is giving empty values. The values of c,g,l,st,nt,L are arbitrary and for example can be considered (3,1,1,1,1,1). Can someone please help me with the error? This is the code.

c = input('c ');
g = input('g '); 
l = input('l ');
st = input('st '); 
nt = input('nt ');
L = input ('L');
syms Lambda_n V_R delta_nrt A_r2
for i = 1:c
    if i <= c-g
        V_R = (l)*kron(kron(A_r2,delta_nrt), eye(nt^(l-1)))  
        C = kron(kron(eye(L),eye(st^(i-1))), V_R)  %error line
        B1 = zeros(c+2-i,c+1-i);
        for j = 1:c+2-i
            for k = 1:c+1-i
 if j==k && j==1 && k==1
     B1(j,k) = 1;
    else B1(j,k) =0
 end
            end
        end
        display(B1)
        A = zeros(size(B1,1)*size(C,1),size(B1,2)*size(C,2),'sym');
        A = kron(B1,C)
        put_A_here=logical([zeros(i,1) eye(i)])
        big=repmat(sym(0),size(put_A_here).*size(A));
        out=big;
        small=A;
        L= put_A_here;
        A=reshape(1:numel(small),size(small));
        B=repmat({zeros(size(A))},size(L));
        B(L)={A};
        B=cell2mat(B);
        B=B(:);
        out(B~=0)=small(B(B~=0));
        D1{i} = out;
    else
        V_R = (l)*kron(kron(A_r2,delta_nrt), eye(nt^(l-1)))  
        C = kron(kron(eye(L),eye(st^(i-1))), V_R) ;            %error line
        B1 = zeros(c+2-i,c+1-i);
        for j = 1:c+2-i
            for k = 1:c+1-i
       if j==k && j==1 && k==1
           B1(j,k) = 1;
       else B1(j,k) =0;
       end
            end
        end
        display(B1)
        A2 = zeros(size(B1,1)*size(C,1),size(B1,2)*size(C,2), 'sym');
        A2 = kron(B1,C)
        put_A_here=logical([zeros(c-g,1) eye(c-g); zeros(1,c-g+1)])
        big=repmat(sym(0),size(put_A_here).*size(A2));
        out=big;
        small=A2;
        L= put_A_here;
        A2=reshape(1:numel(small),size(small));
        B=repmat({zeros(size(A2))},size(L));
        B(L)={A2};
        B=cell2mat(B);
        B=B(:);
        out(B~=0)=small(B(B~=0));
        D1{i} = out;
    end
end
C = blkdiag(D1{:});

[Walter Roberson]

Your L starts as a scalar. For the first round, eye(L) is valid, because L is a scalar. But later you have

        L= put_A_here;

where put_A_here is a vector. Then when eye(L) is used, that fails because eye() does not accept a vector of sizes.

If you are wanting to create an eye() that is L(1) x L(2) then you have to use eye(L(1),L(2)) not eye(L)

[raina RAJ]

Thanks, silly mistake. It's done.