% Linear predictive AOA estimation for a M = 6 element array with noise variance = .1
% allow transpose(u3) = [0 0 1 0 0 0]

M=6;
sig2=.1;
th1=-5*pi/180;
th2=5*pi/180;
a1=[1];
a2=[1];
a=[1];
u3=[0 0 1 0 0 0];
for i=2:M
    a1=[a1 exp(-1j*i*pi*sin(th1))];
    a2=[a2 exp(-1j*i*pi*sin(th2))];
end
A=[a1' a2'];
Rss=[1 0;0 1];
Rrr=A*Rss*A'+sig2*eye(M);
for k=1:180;
   th(k)=-pi/6+pi*k/(3*180);
   clear a
a=[1];
   for jj=2:M
      a = [a exp(-1j*jj*pi*sin(th(k)))];
   end
P(k)=real((u3*inv(Rrr)*u3')/(abs(u3*inv(Rrr)*a.')^2));


end
figure;
plot(th*180/pi,10*log10(P/max(P)),'k')
grid on
xlabel('Angle')
ylabel('|P(\theta)|')
axis([-30 30 -30 10])

%num2str(A,2)