dfdzoomp.m

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

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

% dfdzoomp.m  DFD Zoom attenuation plot
% 1:21  9/3/99
%
%   Authors: Dejan V. Tosic, Miroslav D. Lutovac, 1999.03.08
%                 [e-mail]
%                 [e-mail]
%
%   Copyright (c) 1999 by Tosic & Lutovac
%   $Revision: 1.0 $  $Date: 1999/03/08 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 = 0.5;
 f1 = 0
elseif nargin < 4
 n = 100;
 f2 = 0.5;
elseif nargin < 5
 n = 100;
end

if n<2
 error('DFD ERROR: Number of plot points is less than 2 in DFDZOOMP.');
end
if f1 >= f2
 error('DFD ERROR: f1 >= f2 in DDFZOOMP');
end
if f2 > 0.5
 error('DFD ERROR: f2 > 0.5 in DDFZOOMP');
end

d = (f2-f1)/n;
f = f1:d:f2;
p = 2*pi*f;
H = freqz(num,den,p);
A = -20*log10(abs(H));
plot(f,A)
xlabel('frequency');
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])