Gauss-Seidel method with Successive Over Relaxation

function [X, k, res] = sor(A, b, x0, w, tol, maxIter)
[row, col] = size(A);
n = length(b);
x = x0;
k = 1;
res(k) = tol;
s = 0;
% Check the size of inputs
if (row ~= n) || (col ~= n) disp('Error'); return; end
% Successive over-relaxation method
while res(k) >= tol || k <= maxIter
    for i = 1:n
        for j = 1:i
            if j < i
                s = s + A(i,j) * x(j);
            else
                s = s + A(i,j) * x(j);
            end
        end
        x(i) = (1 - w) * x(i) + w / A(i,i) * (b(i) - s);
    end
    % Check the norm of the residual
    X(k, :) = x;
    k = k + 1;
    res(k) = norm(A * x - b);
    x = x0;
end
end

A = [-4 3 0; 3 -4 -1; 0 -1 4];
b = [-24; 30; 24];
tol = 1e-8;
maxIter = 100;
x0 = [0; 0; 0];
w = 1.25;

[X, iter, res] = sor(A, x0, b, w, tol, maxIter);

Anybody can tell me the issue

Thanks in advance!

Answer 1

[William Rose]

@Muhammad Asif,

Your code includes

            if j < i
                s = s + A(i,j) * x(j);
            else
                s = s + A(i,j) * x(j);
            end

which does the same thing on both sides of the if. Check that section.