n = 2; % Define order
Wn = 1; % Define 3-dB freq in rad/s
Wo = 2*pi*60; % fc in rad/s (Wc)
Wb = 2*pi*2; % fb in rad/s (Wb)
[b,a] = butter(n,Wn,'s'); % Establish analog prototype
[bt,at] = lp2bs(b,a,Wo,Wb); % Convert to bandstop filter
bt % Display numerator coefficients
at % Display denominator coefficifents
% The rest of this file is to do the plot.
w = 2*pi*logspace(1,2,500); % Compute freq. vector in rad/s
h = freqs(bt,at,w); % Compute frequency response
mag = 20*log10(abs(h)); % Determine amplitude response
f=w/(2*pi); % Convert to Hz for plot
semilogx(f,mag) % Execute plot
xlabel('Frequency - Hz') % Label x axis
ylabel('Amplitude Response - dB') % Label y axis
