% Demo of aliassing for a C-major scale1 Dec08
% Four octaves: pure sine wave 261 Hz to 4 kHz
clear all;
disp('==================================');
disp('Demonstrate aliasing for 4-octave scale 261-4kHz');
NH = input('Enter no. of harmonics for each note: ');
Fs = input( 'Enter sampling frequency(Hz):');
Cmaj = [261.62557 293.66477  329.62756  349.2282  391.9954  440  493.8833]; 
Cmaj = [Cmaj Cmaj*2 Cmaj*4 Cmaj*8];  RCmaj = (2*pi/Fs)*Cmaj;
NP = Fs/2;  L = length(Cmaj);
x = zeros(1,NP*L); 
n=1:NP;
for note = 1:L
  Start = 1+(note-1)*NP;
  for i=1:NH
    x(Start:Start+NP-1) =x(Start:Start+NP-1) +(1/NH)*cos(i* RCmaj(note)*n);
  end;
end;   sound(x,Fs);