E = inline('0.5*sum((w-[1:N]/N).^2)','w','N');
dEdw = inline('xx-tt','xx','tt');
fprintf('W(1) = (%f. %f, %f, %f, %f, %f, %f, %f, %f, %f), E(W(1)) = %f \n',w,E(w,N));
tol=1.0e-5;
cost1=E(w,N);
err=2*tol;
k=1;
while err>tol
for i = 1:N
new_w(i) = w(i) - eta*dEdw(w(i),i/N);
end
w=new_w;
fprintf('W(%d) = (%f. %f, %f, %f, %f, %f, %f, %f, %f, %f), E(W(%d))=%f \n', ...
k+1,w,k+1,E(w,N));
cost2=E(w,N);
err=abs(cost2-cost1);
cost1=cost2;
k=k+1;
end