Index in position 2 exceeds array bounds appeared in code, how to fix it?

function [xs, cost, A3] = f_bigM(A,M,n)

nc = 1;
A3(:,:,nc) = A;

%rA = size(A,1);
cA = size(A,2);


% initial problem
j_M = find(A(end,:)==M);

for jj = j_M
    ii = find(A(:,jj)==1);
    k = -A(end,jj)/A(ii,jj);
    A(end,:) = A(end,:)+k*A(ii,:);
end

nc = nc+1;
A3(:,:,nc) = A;

% find basic variables

i_res = (1);
for ii=1:cA
    a = A(:,ii);
    if(norm(a)==sum(a))
        jj = a==1;
        i_res = i_res(ii,jj);
    end
end

soln_exists = 0;
if ( length(unique(i_res(:,2))) == length(i_res(:,2)) )
    xs = zeros(1,cA-1);
    xs(i_res(:,1)) = A(i_res(:,2),end);
    soln_exists = isempty(find(xs < 0, 1));
end

xs = []; cost = [];

if soln_exists
    [xs, cost, A3s] = f_simplex(A,n);
    ns = size(A3s,3);
    A3(:,:,end+1:end+ns) = A3s;
end

Error in line :

if ( length(unique(i_res(:,2))) == length(i_res(:,2)) )

Answer 1

[Cris LaPierre]

This error is a result of using an index that exceeds the size of your array dimension (in this case, the 2nd dimension, or columns). It would appear your variable i_res does not have a 2nd column to index.

a = (1:5)'

a = 5×1

1 2 3 4 5

% There is no second column, so an error message is displayed.
a(:,2)

Index in position 2 exceeds array bounds. Index must not exceed 1.

[Andra Cahaya Khalief]

So how should I write the code?, which section should I fix?

[Cris LaPierre]

I'd start with the line containing the error:

if ( length(unique(i_res(:,2))) == length(i_res(:,2)) )

You haven't shared your variables with us, so all we can do is tell you that 2 does not appear to be a valid index. Try using 1 instead.