function ss = himmelss(k,data)% sum-of-squares for Himmelblau 9.9time = data.ydata(:,1);Aobs = data.ydata(:,2);y0   = data.y0;[t,y] = ode45(@himmelode,time,y0,[],k);Amodel = y(:,1);ss = sum((Aobs-Amodel).^2);