[cherry]

Zt=[1 2 3 4 5 6];
n=length(Zt);
K=n/2;
Z=mean(Zt);
W=Zt-Z;
s=zeros(1,K);
r=zeros(1,K);
p=zeros(1,K);
for k=0:K
A=zeros(1,n-k);
for j=1:n-k
A(j)=W(j)*W(j+k);
s(k)=sum(A);
end
end

??? Subscript indices must either be real positive integers or logicals.

Error in ==> D:\MATLABp6\work\Untitled.m
On line 13 ==> s(k)=sum(A);