n = input('Enter number of data points: ');
t = (2*pi/n)*(0:(n-1));
x = cos(t) + 2*sin(2*t) - sin(3*t); %Generate a simple signal
x = x + 0.1*(-1+2*rand(1,length(x))); %Add random noise to the signal.
z = fft(x);
m = (n-1)/2;
a = real(2*z(1:m+1)/n); %Recover frequency content of signal.
b = -imag(2*z(2:m+1)/n);