simple iterations

%Исходные данные
A = [1,-0.08,0.23,-0.32;
    -0.16,1.23,-0.18,-0.16;
    -0.15,-0.12,0.68,0.18;
    -0.25,-0.21,0.16,0.97;];

B = [1.34,-2.33,0.34,0.63];

%размер системы
N = max(size(B));

%требуемая точность
e = 0.01;

Xprev = zeros(1,N);
roots = zeros(1,N);

m = max(abs(root));

while m > e
    for i = 1:N
        ss = 0;
        for j = 1:N
            if (i ~= j)
                ss = ss + A(i,j) * Xprev(j);
            end;
        end
        roots(i) = (B(i) - ss)/A(i,i);
    end
    m = max(abs(roots - Xprev));
    Xprev = roots;
end;

disp(roots)