Example 1: Input Signal

% Signal parameters:
f = [ 440 880 1000 2000 ];      % frequencies   
M = 256;                        % signal length 
Fs = 5000;                      % sampling rate

% Generate a signal by adding up sinusoids:
x = zeros(1,M); % pre-allocate 'accumulator'
n = 0:(M-1);    % discrete-time grid 
for fk = f; 
    x = x + sin(2*pi*n*fk/Fs); 
end

Input Signal: Time-Domain Waveform