function [x,m]=sor(A,b,w,kmax)
n=length(b);
x=zeros(n,1);
xk=zeros(n,1);
e=0.00001;
for k=1:kmax
    xk=x;
    for i=1:n
        sum=0;
        for j=1:n
            if j~=i
                sum=sum+A(i,j)*x(j);
            end
        end
        x(i)=(b(i)-sum)/A(i,i);
        x(i)=xk(i)+w*(x(i)-xk(i));
    end
    if norm(x-xk,1)<e
        m=k-1;
        break;
    end
end
if norm(x-xk,1)>e
    disp('iterative times reach upper limit');
end

end