function pow_rq(A);

 [n,n] = size(A);
 s = eig(A);
 [d,ii] = max(abs(s));
 lam0 = s(ii);
 t = zeros(20,1);
 s = lam0*ones(20,1);

 v =  randn(n,1); v = v/norm(v);
 for j = 1:20,
    w = A*v;
    lam = v'*w;
    v = w/norm(w);
    t(j) = lam;
 end
 format long e
 lambda_vals_RQ = [t abs(t-s)]