title: Help me understand FFT function (Matlab)
body: <p>1) Besides the negative frequencies, which is the minimum frequency provided by the FFT function? Is it zero?<br>
  2) If it is zero how do we plot zero on a logarithmic scale?<br>
  3) The result is always symmetrical? Or it just appears to be symmetrical?<br>
  4) If I use abs(fft(y)) to compare 2 signals, may I lose some accuracy?</p>