Getting a Index exceeds matrix dimension Error. Can someone explain how to fix this?

THE EEROR IS IN LINE 16, THE CODE IS AS FOLLOWS:

A=input('Enter Matrix A ');
b=input('Enter matrix b ');
tol=input('Enter tolerance ');
iter=0;
n=length(A);
x1=zeros(length(A),1)
x2=zeros(length(A),1)
err=.1
% for i=1:100
   while err<tol
    for i=1:n
        for j=1:n
             if i~=j
                x2(i)=x2(i)+((-A(i,j)*x1(j)/A(i,i))+(b(i)/A(i,i)))
             x2(i)=x2(i)+x1(i)
                x2(i)=sqrt((x2(i)^(2)))
             end
        end

      iter=iter+1

     end
       err=(norm(x2)-norm(x1))/norm(x1)
      x1(i)=x2(i)
  end

[John Chilleri]

Your code operates under the assumption that A is n x n (square). Also, I think you should change your input to request a vector b.

If matrix A is not square, then it may produce your error when you access A(i,j). Also, using

length(A)

is strange since A is a matrix.

Consider using

size(A,1) or size(A,2)

depending on which dimension size you desire.

Hope this helps!