function [res,sol] = CG (A, rhs, x0, m, tol) 
%%--------------------------------------------------
% CG (A, x, rhs, m, tol) 
% x0  = initial guess on entry -- 
% rhs = rhs, m = number of steps 
% m   = max number of steps 
% tol = tolerance
% res = residuals.. 
% sol = app sol on return 
%%--------------------------------------------------
 sol = x0; 
 r = rhs - A * sol;
 p = r ; 
 ro1 = r' * r; 
 res(1) = sqrt(ro1) ;
 tol1 = tol*tol*ro1; 
%
 j = 0; 
 while (j < m & ro1 > tol1) 
	 j = j+1; 
	 ro = ro1; 
	 ap = A * p; 
	 alp = ro / ( p'*ap ) ;
	 sol = sol + alp * p ;
	 r = r - alp * ap; 
	 ro1= r'*r;
         res(j+1) = sqrt(ro1) ;
	 bet = ro1 / ro ;
	 p = r + bet * p; 
  end
 end