function [x]=gass_siedeldejen(A,b,x0,tol,itr)
x=x0;
n=size(x,1);
normVal=Inf; 
disp('      i         x1       x2        x3       x4')
while normVal>tol
    x_old=x;
    for i=1:n    
        sigma=0;  
        for j=1:i-1
                sigma=sigma+A(i,j)*x(j);
        end    
        for j=i+1:n
                sigma=sigma+A(i,j)*x_old(j);
        end  
        x(i)=(1/A(i,i))*(b(i)-sigma);
    end   
    itr=itr+1;
    disp([itr  x'])
    normVal=norm(x_old-x);
end
end