format compact
format short
echo on
clc
% Generate a complex exponential spiral
% Start with a point on the unit circle
a = pi/4;
z = cos(a) + i*sin(a);
pause
% Move it in a bit
z = .99*z;
pause
% Make the exponential sequence
n = 1:100;
x = z.^n;
% Plot it
figure(1)
plot3(real(x), imag(x), n)
grid on
axis square
pause
% Make a random impulse response 
%      & convolve it with x
h = rand(5,1);
y = conv(h,x);
% Avoid edge effects 
y1 = y(5:100);
n1 = n(1:96);
x1 = x(1:96);
pause
% Plot the result
figure(2)
plot3(real(y1), imag(y1), n1)
grid on
axis square
pause
% What's the "eigenvalue" (i.e. H(z))?
y1./x1