G=tf([1,7,24,24],[1,10,35,50,24]);v=covar(G,1);
xx=linspace(-2.5,2.5,30);yy=hist(yout,xx);
yy=yy/(length(yout)*(xx(2)-xx(1)));
yp=exp(-xx.^2/(2*v))/sqrt(2*pi*v);
bar(xx,yy),hold on;plot(xx,yp);