t = 0:.001:1; % n = 1001 
freq = 1:1:1001; 
fftsin = fft(4*sin(2*pi*40*t)); 
fftcos = fft(8*cos(2*pi*100*t)); 
subplot(2,1,1); 
plot(freq,real(fftsin),freq,real(fftcos));
subplot(2,1,2); 
plot(freq,imag(fftsin),freq,imag(fftcos));