In a 6x6 square matrix A, how to select elements in i-th row with A(i,j) ruled out

n=12;
A=zeros(n,n);
B=zeros(n,n);
if A(i,(i-1):(i+1):n)==0
    B(i,i)=1;
end

[Stephen23]

are you looking for one of these?:

eye(6)

ans = 6×6

1 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 1

1-eye(6)

ans = 6×6

0 1 1 1 1 1 1 0 1 1 1 1 1 1 0 1 1 1 1 1 1 0 1 1 1 1 1 1 0 1 1 1 1 1 1 0

[godspeed]

Forgive me as the question was confusing. The question should be: say A is 4x4 square matrix and B=zeros(4,4). If the i-th diagonal element of A is 1 and all the non-diagonal elements are 0 in that i-th row, then B(i,i)=1. In this case, B(3,3)=1 and all other elements should be 0.

A =

0 0 -1 1

1 1 0 0

0 0 1 0

1 -1 0 1

Answer 1

[KSSV]

A = [0     0    -1     1
     1     1     0     0
     0     0     1     0
     1    -1     0     1] ;
 
 B = zeros(size(A)) ;
 for i = 1:4
     if A(i,i) == 1  % if disagonal element = 1 
         temp = A(i,:) ; % get the ith row 
         temp(i) = [] ;  % remove the diagonal element 
         if ~any(temp)  % check whether all are zeros 
            B(i,i) = 1 ;  % Make B(i,i) = 1 
         end
     end
 end
 B

B = 4×4

0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0

[godspeed]

Thank you so much.

Answer 2

[Stephen23]

A = [0,0,-1,1;1,1,0,0;0,0,1,0;1,-1,0,1]

A = 4×4

0 0 -1 1 1 1 0 0 0 0 1 0 1 -1 0 1

B = +diag(diag(A) & ~any(A-eye(size(A)),2))

B = 4×4

0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0