Function: fftindex

FFTINDEX  Frequency index of FFT modulations
  Usage: n=fftindex(N);

  FFTINDEX(N) returns the index of the frequencies of the standard FFT of
  length N as they are ordered in the output from the fft routine. The
  numbers returned are in the range -ceil(N/2)+1:floor(N/2)

  FFTINDEX(N,0) does as above, but sets the Nyquist frequency to zero.

Url: http://ltfat.github.io/doc/fourier/fftindex.html

See also: dft.

Package: ltfat