"Nasser M. Abbasi" <email@example.com> wrote in message <firstname.lastname@example.org>... > On 11/15/2012 2:33 AM, oversky wrote: > > The mathwork fft example in the following link, > > http://bit.ly/SO9TuV > > why do we double abs(Y(1:NFFT/2+1) when plotting the amplitude? > > > > plot(f,2*abs(Y(1:NFFT/2+1))) > > > > This was talked about before. can google it. Here is my take on it: > > "Why does it multiply by 2?" > > http://12000.org/my_notes/on_scaling_factor_for_ftt_in_matlab/index.htm
To represent the same average power as the doublesided frequency representation.
the DC and Nyquist components should NOT be doubled.