INDEX IN POSITION 1 EXCEEDS ARRAY BOUNDS (MUST NOT EXCEED 3)

Index in position 1 exceeds array bounds. Index must not exceed 3.

Error in untitled3 (line 17)

Sum = Sum + a(i,j)*x(j);

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a = [1.44,-0.36,5.52,0.00;-0.36,10.33,-7.78,0.00;5.52,-7.78,28.40,9.00];
b = [0.04;-2.15;0;0.88];
n = length(b);
x = zeros(n,1);
xnew = zeros(n,1);

x(:) = 0;
iterlimit = 100;
tol = 1e-6;

for iteration = 1 : iterlimit
    convergence = true;
    for i = 1 : n 
        Sum = 0;
        for j = 1 : n
            if j ~= i
                Sum = Sum + a(i,j)*x(j);
            end
        end
        xnew(i) = -1/a(i,i) * (Sum -b(i));
        if abs(xnew(i) - x(i)) > tol
            convergence = false;
        end
    end
    if convergence
        break
    end
    x = xnew;
end
disp('iterations')
iter
disp('solution')
xnew;

[Laura Ashley Signo]

I need it for my programming project and I dont know how to solve it. Thank you!

Answer 1

[Star Strider]

These —

for i = 1 : n

Sum = 0;

for j = 1 : n

should instead be —

for i = 1 : size(a,1)

Sum = 0;

for j = 1 : size(a,2)

Try that.

.

[Laura Ashley Signo]

Thank you!!! It works!!! Thank you thank you so much!

[Star Strider]

As always, my pleasure!

.