Since the th spectral sample
is properly regarded as
a measure of spectral amplitude over a range of frequencies,
nominally to , this range is sometimes called a
frequency bin
(as in a ``storage bin'' for spectral energy).
The frequency index is called the bin number, and
can be regarded as the total energy in the th
bin (see §7.4.9).
Similar remarks apply to samples of any
bandlimited
function; however, the term ``bin'' is only used in the frequency
domain, even though it could be assigned exactly the same meaning
mathematically in the time domain.