fft

Hi everyone,

I have a vector (array) that include 128 values (for 128 samples of signal) and I want to do fft transform for this vector, if I use fft function of matlab I get 128 values... My goal is to get one value that represent a fft transform (because dft-or fft- transform contain a sigma and it should be a sum of amplitudes * e^j...) Is there any function of matlab that do this? or I should to sum the elements of the fft output? or maybe Im missimg something in fft understanding?

Thanks,

Answer 1

[Walter Roberson]

The sum of the amplitudes of the signal is the first element of the fft() output.

But if all you want is the sum of the amplitudes of the signal, it would seem less expensive to just sum the signal samples themselves.