5.1

close all
clear all
p(1) = -0.5 + 1i*9.5;
p(2) = -0.5 - 1i*9.5;
p(3) = -1 + 1i*10;
p(4) = -1 - 1i*10;
p(5) = -0.5 + 1i*10.5;
p(6) = -0.5 - 1i*10.5;

z(1) = 1i*5;
z(2) = -1i*5;
z(3) = 1i*15;
z(4) = -1i*15;

N = length(z);
M = length(p);

w = 0:0.1:20;

a = 1;
for i=1:N
    a = a .* (1i*w - z(i));
end

b = 1;
for i = 1:M
    b = b .* (1i*w - p(i));
end

figure(1)
plot(real(z),imag(z),'or',real(p),imag(p),'*b');grid;

H = abs(a./b);
figure(2)
plot(w,H)
figure(3)
semilogy(w,H)