function ps71(a)
if nargin<1, a=0; end
s=tf('s');
p=ss(a,[1 1],[1;1],[0 1;1 0]);
[K1,~,GAM1]=h2syn(p,1,1);   % numerical solution
if a>1,
    K=-(1-2*a)^2/(s-2+3*a);
    GAM=sqrt((2*a-2)*(1+(1-2*a)^2));
else
    K=-1/(s+2-a);
    GAM=0;
end
fprintf('GAMMA: analytical %f, numerical %f\n',GAM,GAM1)
K=tf(K)
K1=tf(K1)