function count = GS(omega)
% This performs Over-Relaxed Gauss-Seidel on the matrix given below
% Input: omega = relaxation factor
% Output: number of iterations required for convergence
A = [ -4  1   1  1;
       1 -4   1  1;
       1  1  -4  1;
       1  1   1 -4];
b = [1 1 1 1 ]';
% actual solution is [-1 -1 -1 -1]'
x = [0 0 0 0]';
tol = 10^(-5);
[n,m] = size(A);
Res = b - A*x;
sizeRes = norm(Res,2);
count = 0;
maxits = 300;
while sizeRes > tol
    for i=1:n
        Res(i) = b(i) - A(i,:) * x;
        x(i) = x(i) + omega * Res(i)/A(i,i);
    end
    sizeRes = norm(Res,2);
    count = count+1;
    if count > maxits
        disp('Did not converge!!!!!')
        sizeRes = 0;
    end    
end