Help me to fix it because the error said Attempted to access xnew(2); index out of bounds because numel(xnew)=1. Error in jacobi (line 22) err = norm(xnew(i)-x(i),Inf)/norm(xnew(i),Inf);

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Nur Syafawani Mat Syet 2018-10-29

0
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https://ww2.mathworks.cn/matlabcentral/answers/426675-help-me-to-fix-it-because-the-error-said-attempted-to-access-xnew-2-index-out-of-bounds-because-nu

回答： Torsten 2018-10-29

a = [1, 0, -1; -1/2, 1, -1/4;1, -1/2, 1];
b = [0.2; -1.425; 2];
n = length(b);
x = zeros(n,1);
xnew = zeros(n,1);
x(:) = 0;
iterlimit = 3;
tol = 0.001;
for iteration = 1 : iterlimit
    convergence = true;
    for i=1 : n %loop of equtions
        sum = 0;
        for j = 1: n % loop of summation
            if j~= i
                sum = sum + a(i,j) * x(j)
            end;
        end;
        xnew = -(1/a(i,i)) * (sum - b(i));
          err = norm(xnew(i)-x(i),Inf)/norm(xnew(i),Inf);
          if err <0 tol
              convergence = false;
          end;  
      end;
      if convergence
          break
      end
      x = xnew;
  end;
  disp('iteration: ')
  iter
  disp('solution: ')
  xnew