function [g,d]=ps22a(p)
% function [g,d]=ps22a(p)
% 
% given p>0 (default p=0.25) minimize r=g^2 subject to
%  r|w|^2-|y|^2>d(w'y-p|y|^2)
if nargin<1, p=0.25; end
r=msspoly('r');          % r
w=msspoly('w');          % w
y=msspoly('y');          % y
d=msspoly('d');          % d
q=msspoly('Q',3);        % coefficients of Q
pr = mssprog;            % initialize program
pr.free = r;             % register r
pr.pos = d;              % register d
pr.psd = q;              % register q
Q = mss_v2s(q);          % symmetric Q
z = [w;y];                     
pr.eq = r*w^2-y^2-d*(w*y-p*y^2)-z'*Q*z; 
pr.sedumi = r;           % minimize r
g=sqrt(pr({r}));         % L2 gain bound
d=pr({d});