I need to extract rows from the big matrix 'k' and store it in different matrix using 'for' loop?

function y=Mid_terms(x)
format long;
m=1;
n=1;
N=length(x);
for i=4:N-4
    for j=i-3:i+3
        for k=0:10
            F(m)=((x(j)-x(i))^(k))/(factorial(k));
            y(n)=F(m);
            m=m+1;
            n=n+1;
        end
    end
end
k=reshape(y,[28,121]);
b=[0;0;1;0;0;0;0;0;0;0;0];

[dpb]

So, explain the problem...