N
7;
p=1/2;
q=1/2;

Q=zeros(N,N);

for i=2:N-1
    Q(i,i+1)=q;
    Q(i,i-1)=p;
end

Q(1,2)=q;
Q(1,N)=p
Q(N,N-1)=p;
Q(N,1)=q;
pause
iter=100;
Pold=zeros(N,1);
Pold((N-1)/2,1)=1;

Psave=[Pold];

for k=1:iter
Pnew=Q*Pold;
Pold=Pnew;
Psave=[Psave Pold];
end

figure(1)
imagesc(Psave)
figure(2)
for i=1:N
    plot(Psave(i,:))
    pause
    hold on
end