%% L07_DTFT
%% ==============
%% Script to illustrate DTFT plots: See lecture07, DTFT Example 2
%%
%% Created  : 07 Aug 2005
%% Modified : 07 Aug 2005
%%
%% Copyright (c) 2005 Salman Durrani .
%% ------------------------------------------------------------

clc
clear all
close all

%% Define transfer function
%% h[n]=a^n u[n] , H(z)=z/(z-a)
a=0.5;
num=[1];
den=[1 -a];

%% ------------------------------------------------------

%% Define the frequency vector
w = [-pi:0.1:pi];
%% Calculate frequency response
[H, W]= freqz(num,den,w);

%% ------------------------------------------------------

%% Magnitude response
figure
plot(W,abs(H))
axis([-pi pi -Inf Inf])
%% Phase response
figure
plot(W,angle(H)*180/pi)
axis([-pi pi -180 180])

%% ------------------------------------------------------

%% Bode plot
freqz(num,den,w);

%% ------------------------------------------------------

%% Alternative: use Filter Vizualization Tool
fvtool(num,den)

%% ------------------------------------------------------