% ECE 321 Lecture #8
% Cost function for a filter

function [ J ] = cost_filter( z )
 a = z(1);
 b = z(2);
 c = z(3);
 d = z(4);
 e = z(5);
 w = [0:0.1:10]';
 s = j*w;
 Gideal = 1 * (w < 3);
 G = a ./ ( (s.^2 + b*s + c).*(s.^2 + d*s + e) );
 e = abs(Gideal) - abs(G);
 J = sum(e .^ 2);
 plot(w,abs(Gideal),'r',w,abs(G),'b');
 ylim([0,1.2]);
 pause(0.01);
end