The Jacobi method implemented in Octave.

jacobi.m

function xnew = jacobi(A, b, xold)
  % This is a sample implementation of the Jacobi method in
  % Octave. 
  
  % We first need to determine how many equations there are
  % that we need to solve
  n = size(A, 1);
  % We create a blank xnew vector to store the final results
  xnew = zeros(n, 1);
  
  for k = 1:n
    % We first get the diagonal value so that we can set it 
    % to null in the matrix
    diagonal_value = A(k,k);
    
    % Set the diagonal value to 0 so it doesn't affect our
    % future calculations
    A(k,k) = 0;
    
    % We then calculate a new xnew value using the xold vector
    xnew(k) = (b(k) - A(k,:)*xold) / diagonal_value;
  endfor
endfunction

thanksX!

genius!