afdzoomp.m

AFD - Advanced Filter Design using MATLABMiroslav D. Lutovac, Dejan V. Tosicversion 1.00 released 15

function afdzoomp(num,den,f1,f2,n,order)

% afdzoomp.m  AFD Zoom attenuation plot
% 1:02  3/2/99
%
%   Authors: Dejan V. Tosic, Miroslav D. Lutovac, 1999.02.08
%                 [e-mail]
%                 [e-mail]
%
%   Copyright (c) 1999 by Tosic & Lutovac
%   $Revision: 1.0 $  $Date: 1999/02/08 03:07:42 $
%
%   References:
%        Miroslav D. Lutovac, Dejan V. Tosic, Brian L. Evans
%           Advanced Filter Design for Signal Processing
%                   Using MATLAB and Mathematica

if nargin < 3
 n = 100;
 f2 = 2;
 f1 = 0
elseif nargin < 4
 n = 100;
 f2 = 2*f1;
elseif nargin < 5
 n = 100;
end

if n<2
 error('AFD ERROR: Number of plot points is less than 2 in AFDZOOMP.');
end
if f1 > f2
 error('AFD ERROR: f1 > f2 in ADFZOOMP');
end

d = (f2-f1)/n;
f = f1:d:f2;
s = j*2*pi*f;
H = polyval(num,s)./polyval(den,s);
A = -20*log10(abs(H));
plot(f,A)
xlabel('frequency (Hz)');
ylabel('attenuation (dB)');
title(['Attenuation characteristic',' (order=',num2str(order),')']);
a = axis;
a(1) = f1;
a(2) = f2;
axis(a);

set(gca,'Color',[0.45 0.55 0.45])